Hexen has begun crashing whenever changing levels (any level I've tried) -- this happen consistently between map01 and map02. This started after I added a modified version of "xmusic.pk3" in which I added my own remakes of some of the soundtrack. But I turned off the "external music" and got rid of " "xmusic.pk3," but still got the same crash. I no longer have any idea what causes this, or how / if the music is related.

Init: Adding ./basev/common/basepak.pk3
Init: adding ./hexen.wad
Init: adding ./hexen.gwa
Init: Adding ./basev/hexen/basepak.pk3
Init: Adding ./basev/hexen/xflats.pk3
Init: Adding ./basev/hexen/xgfx.pk3
Init: Adding ./basev/hexen/xmodels.pk3
Init: Adding ./basev/hexen/xmusic.pk3
Init: Adding ./basev/hexen/xwalls.pk3
Init: Selected DirectSound sound device
Init: ======================================
Init: Initialising DirectSound driver.
Init: 3D sound on
Init: IKsPropertySet acquired
Init: EAX 2.0 supported
Init: Selected Windows multimedia system midi device
Init: Selected Windows CD audio device
Dev: CDAudio: drive not ready
Init: CDAudio_Init: No CD in player.
Init: CD Audio Initialised
Init: Using 60 sound buffers
Init: Selected Win32 OpenGL rasteriser device
Init: Processing DECORATE scripts
Log: No such class Chicken
Log: No such class ChickenPlayer
Log: No such class Staff
Log: No such class GoldWand
Log: No such class PunchDagger
Log: actors/strife/strifebishop.txt:58: warning: No such class AlienSpectre2
Init: Parsing effect defs
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such sprite tfog
Init: No such class ScriptedMarine
Init: No such class MarineFist
Init: No such class MarineBerserk
Init: No such class MarineChainsaw
Init: No such class MarinePistol
Init: No such class MarineShotgun
Init: No such class MarineSSG
Init: No such class MarineChaingun
Init: No such class MarineRocket
Init: No such class MarinePlasma
Init: No such class MarineBFG
Init: No such class MarineRailgun
Init: No such class Volcano
Init: No such class VolcanoBlast
Init: No such class VolcanoTBlast
Init: No such class TeleGlitter1
Init: No such class TeleGlitter2
Init: No such class ActivatedTimeBomb
Init: No such class Pod
Init: No such class Sorcerer2
Init: No such class HereticImpBall
Init: No such class KnightAxe
Init: No such class RedAxe
Init: No such class Wizard
Init: No such class WizardFX1
Init: No such class Ironlich
Init: No such class HeadFX1
Init: No such class HeadFX2
Init: No such class HeadFX3
Init: No such class SorcererFX1
Init: No such class Sorcerer2FX1
Init: No such class Sorcerer2FX2
Init: No such class Sorcerer2Telefade
Init: No such class StaffPuff2
Init: No such class GauntletPuff1
Init: No such class GauntletPuff2
Init: No such class GoldWandPuff1
Init: No such class GoldWandPuff2
Init: No such class GoldWandFX2
Init: No such class CrossbowFX1
Init: No such class CrossbowFX2
Init: No such class CrossbowFX3
Init: No such class BlasterPuff
Init: No such class BlasterFX1
Init: No such class HornRodFX1
Init: No such class HornRodFX2
Init: No such class RainPillar
Init: No such class RainPlayer2
Init: No such class RainPlayer3
Init: No such class RainPlayer4
Init: No such class PhoenixFX1
Init: No such class PhoenixFX2
Init: No such sprite alco
Init: No such sprite alco
Init: No such class KlaxonWarningLight
Init: No such class Computer
Init: No such class PowerCrystal
Init: No such class DegninOre
Init: No such class AcolyteBlue
Init: No such class AcolyteDGreen
Init: No such class AcolyteGold
Init: No such class AcolyteGray
Init: No such class AcolyteLGreen
Init: No such class AcolyteRed
Init: No such class AcolyteRust
Init: No such class AcolyteShadow
Init: No such class AcolyteTan
Init: No such class Rebel1
Init: No such class Rebel2
Init: No such class Rebel3
Init: No such class Rebel4
Init: No such class Rebel5
Init: No such class Rebel6
Init: No such class Macil1
Init: No such class Macil2
Init: No such class Templar
Init: No such class Stalker
Init: No such class Sentinel
Init: No such class SentinelFX1
Init: No such class SentinelFX2
Init: No such class CeilingTurret
Init: No such class Reaver
Init: No such class Crusader
Init: No such class CrusaderMissile
Init: No such class Inquisitor
Init: No such class InquisitorShot
Init: No such class Programmer
Init: No such class ProgrammerBase
Init: No such class ElectricBolt
Init: No such class MiniMissile
Init: No such class HEGrenade
Init: No such class PhosphorousFire
Init: No such class FlameMissile
Init: No such class FastFlameMissile
Init: No such class MaulerTorpedo
Init: No such class MaulerTorpedoWave
Init: No such class SpectralLightningBall1
Init: No such class SpectralLightningBall2
Init: No such class SpectralLightningV1
Init: No such class SpectralLightningV2
Init: No such class SpectralLightningBigBall1
Init: No such class SpectralLightningBigBall2
Init: No such class SpectralLightningBigV1
Init: No such class SpectralLightningBigV2
Init: No such class SpectralLightningH1
Init: No such class SpectralLightningH2
Init: No such class SpectralLightningH3
Log: Executing startup.vs
Log: Executing default.cfg
Log: Executing config.cfg
Log: Can't find autoexec.cfg
Log: 1024x768x32.
Init: GL_VENDOR: ATI Technologies Inc.
Init: GL_RENDERER: RADEON XPRESS 200 Series SW TCL x86/SSE2
Init: GL_VERSION: 1.4.5645 WinXP Release
Init: GL_EXTENSIONS:
Init: - GL_ARB_multitexture
Init: - GL_EXT_texture_env_add
Init: - GL_EXT_compiled_vertex_array
Init: - GL_S3_s3tc
Init: - GL_ARB_depth_texture
Init: - GL_ARB_fragment_program
Init: - GL_ARB_fragment_program_shadow
Init: - GL_ARB_fragment_shader
Init: - GL_ARB_multisample
Init: - GL_ARB_occlusion_query
Init: - GL_ARB_point_parameters
Init: - GL_ARB_point_sprite
Init: - GL_ARB_shader_objects
Init: - GL_ARB_shading_language_100
Init: - GL_ARB_shadow
Init: - GL_ARB_shadow_ambient
Init: - GL_ARB_texture_border_clamp
Init: - GL_ARB_texture_compression
Init: - GL_ARB_texture_cube_map
Init: - GL_ARB_texture_env_add
Init: - GL_ARB_texture_env_combine
Init: - GL_ARB_texture_env_crossbar
Init: - GL_ARB_texture_env_dot3
Init: - GL_ARB_texture_mirrored_repeat
Init: - GL_ARB_transpose_matrix
Init: - GL_ARB_vertex_blend
Init: - GL_ARB_vertex_program
Init: - GL_ARB_vertex_shader
Init: - GL_ARB_window_pos
Init: - GL_ARB_draw_buffers
Init: - GL_ATI_draw_buffers
Init: - GL_ATI_envmap_bumpmap
Init: - GL_ATI_fragment_shader
Init: - GL_ATI_separate_stencil
Init: - GL_ATI_texture_env_combine3
Init: - GL_ATI_texture_float
Init: - GL_ATI_texture_mirror_once
Init: - GL_ATI_vertex_streams
Init: - GL_ATIX_texture_env_combine3
Init: - GL_ATIX_texture_env_route
Init: - GL_ATIX_vertex_shader_output_point_size
Init: - GL_EXT_abgr
Init: - GL_EXT_bgra
Init: - GL_EXT_blend_color
Init: - GL_EXT_blend_func_separate
Init: - GL_EXT_blend_minmax
Init: - GL_EXT_blend_subtract
Init: - GL_EXT_clip_volume_hint
Init: - GL_EXT_draw_range_elements
Init: - GL_EXT_fog_coord
Init: - GL_EXT_framebuffer_object
Init: - GL_EXT_multi_draw_arrays
Init: - GL_EXT_packed_pixels
Init: - GL_EXT_point_parameters
Init: - GL_EXT_rescale_normal
Init: - GL_EXT_secondary_color
Init: - GL_EXT_separate_specular_color
Init: - GL_EXT_shadow_funcs
Init: - GL_EXT_stencil_wrap
Init: - GL_EXT_texgen_reflection
Init: - GL_EXT_texture3D
Init: - GL_EXT_texture_compression_s3tc
Init: - GL_EXT_texture_cube_map
Init: - GL_EXT_texture_edge_clamp
Init: - GL_EXT_texture_env_combine
Init: - GL_EXT_texture_env_dot3
Init: - GL_EXT_texture_filter_anisotropic
Init: - GL_EXT_texture_lod_bias
Init: - GL_EXT_texture_mirror_clamp
Init: - GL_EXT_texture_object
Init: - GL_EXT_texture_rectangle
Init: - GL_EXT_vertex_array
Init: - GL_EXT_vertex_shader
Init: - GL_HP_occlusion_test
Init: - GL_NV_blend_square
Init: - GL_NV_occlusion_query
Init: - GL_NV_texgen_reflection
Init: - GL_SGI_color_matrix
Init: - GL_SGIS_generate_mipmap
Init: - GL_SGIS_multitexture
Init: - GL_SGIS_texture_border_clamp
Init: - GL_SGIS_texture_edge_clamp
Init: - GL_SGIS_texture_lod
Init: - GL_SUN_multi_draw_arrays
Init: - GL_WIN_swap_hint
Init: - WGL_EXT_extensions_string
Init: - WGL_EXT_swap_control
Init: Maximum texture size: 2048
Init: Found GL_ARB_multitexture...
Init: Multitexture extensions found.
Init: Max anisotropy 16.000000
Init: Clamp to edge extension found.
Dev: Spawning server map01
Dev: Server spawned
Log: ---------------------------------------
Log: WINNOWING HALL
Log: 
Dev: 159 subdivides
Dev: 662 seg subdivides
Dev: 70k light mem
Dev: Client level loaded
Log: >killall
Log: 24 MONSTERS KILLED
Log: >gimme weapons
Log: ALL WEAPONS
Log: >gimme keys
Log: ALL KEYS
Log: QUARTZ FLASK
Log: CRYSTAL VIAL

Unfortunately, your log doesn't has any information that could be used to track the problem down <!-- s:( --><img src="{SMILIES_PATH}/icon_sad.gif" alt=":(" title="Sad" /><!-- s:( -->.

Works fine here.

Still having this problem, though only when using OpenGL (don't know why), but it works fine if I set the rendering to software.

If it only happens when using OpenGL, probably a problem with your video card, have you tried looking for updated drivers? Also, if possible, test using Direct3d (if you are on windows, of course).