I have the same problem. This is the backtrace I got from gdb:
#0 0xb31fac4e in rgb565_image () from /usr/lib/i386-linux-gnu/libtxc_dxtn.so
No symbol table info available.
#1 0xb31fdc39 in tx_compress_dxtn ()
from /usr/lib/i386-linux-gnu/libtxc_dxtn.so
No symbol table info available.
#2 0xb2db4240 in _mesa_texstore_rgb_dxt1 ()
from /usr/lib/i386-linux-gnu/libdricore9.0.0.so.1
No symbol table info available.
#3 0xb2dd5bed in _mesa_texstore ()
from /usr/lib/i386-linux-gnu/libdricore9.0.0.so.1
No symbol table info available.
#4 0xb2dd5e63 in ?? () from /usr/lib/i386-linux-gnu/libdricore9.0.0.so.1
No symbol table info available.
#5 0xb2dd60f6 in _mesa_store_teximage ()
from /usr/lib/i386-linux-gnu/libdricore9.0.0.so.1
No symbol table info available.
#6 0xb30a7a2d in ?? () from /usr/lib/i386-linux-gnu/dri/i965_dri.so
No symbol table info available.
#7 0xb2dc1906 in ?? () from /usr/lib/i386-linux-gnu/libdricore9.0.0.so.1
No symbol table info available.
#8 0xb2dc2b7e in _mesa_TexImage2D ()
---Type <return> to continue, or q <return> to quit---
from /usr/lib/i386-linux-gnu/libdricore9.0.0.so.1
No symbol table info available.
#9 0x080fa6cd in R_UploadTexture (data=0xafd79008, width=1024, height=768,
image=0x9e7d77c <r_images+12284>) at src/client/renderer/r_image.c:328
scaled = 0xaf978034
scaledWidth = 1024
scaledHeight = 1024
samples = 33776
i = 786432
c = 786432
scan = 0xb007900b ""
mipmap = qfalse
clamp = qtrue
__PRETTY_FUNCTION__ = "R_UploadTexture"
#10 0x080fae42 in R_LoadImageData (name=0xbffff00c "pics/background/mail_bg",
pic=0xafd79008 "xxx\377yyy\377{{{\377|||\377}}}\377}}}\377~~~\377\177\177\177\377~~~\377}}}\377|||\377xxx\377www\377uuu\377ppp\377nnn\377ooo\377ooo\377ooo\377ooo\377ooo\377ppp\377ooo\377kkk\377fff\377eee\377fff\377ccc\377___\377___\377```\377ccc\377ggg\377kkk\377mmm\377nnn\377nnn\377ppp\377ooo\377kkk\377ggg\377ggg\377ggg\377ggg\377ggg\377eee\377ggg\377hhh\377fff\377jjj\377"..., width=1024,
height=768, type=it_pic) at src/client/renderer/r_image.c:496
---Type <return> to continue, or q <return> to quit---
image = 0x9e7d77c <r_images+12284>
images = 0x9e7a780 <r_images>
i = 83
len = 23
hash = 57
__PRETTY_FUNCTION__ = "R_LoadImageData"
#11 0x080fb21d in R_FindImage (
pname=0x971d260 <string.4410+12288> "pics/background/mail_bg", type=it_pic)
at src/client/renderer/r_image.c:582
lname = "pics/background/mail_bg\000\206Y\254\267X\360\377\277\275_\022\b`\322q\t\000\020\000\000$B\032\bd\360\377\277\000\000\000\000 \222\000\005d\360\377\277"
image = 0x0
surf = 0xabff438
#12 0x08093ffd in UI_LoadImage (name=0xb103ea44 "background/mail_bg")
at src/client/ui/ui_render.c:76
image = 0x8123d05 <UTF8_strncpyz+176>
#13 0x080a250a in UI_ImageNodeLoaded (node=0xb103e910)
at src/client/ui/node/ui_node_image.c:63
image = 0xb103e910
#14 0x08093167 in UI_ParseNode (parent=0xb103e720, text=0xbffff1c8,
---Type <return> to continue, or q <return> to quit---
token=0xbffff168,
errhead=0x81a3da4 "UI_ParseWindow: unexpected end of file (window")
at src/client/ui/ui_parse.c:1110
node = 0xb103e910
behaviour = 0x82aca80 <nodeBehaviourList+4416>
component = 0x0
result = qtrue
#15 0x08092d57 in UI_ParseNodeBody (node=0xb103e720, text=0xbffff1c8,
token=0xbffff168,
errhead=0x81a3da4 "UI_ParseWindow: unexpected end of file (window")
at src/client/ui/ui_parse.c:991
newNode = 0x28
result = qtrue
#16 0x08093879 in UI_ParseWindow (type=0x94b77c0 <headerType.8245> "window",
name=0x94b7800 <headerName.8246> "mailclient", text=0xbffff1c8)
at src/client/ui/ui_parse.c:1336
errhead = 0x81a3da4 "UI_ParseWindow: unexpected end of file (window"
window = 0xb103e720
token = 0x9719220 <com_token> "}"
result = qtrue
i = 61
---Type <return> to continue, or q <return> to quit---
#17 0x08058f98 in CL_ParseClientData (
type=0x94b77c0 <headerType.8245> "window",
name=0x94b7800 <headerName.8246> "mailclient", text=0xbffff1c8)
at src/client/cl_main.c:812
progressCurrent = 1464
#18 0x080d9360 in Com_ParseScripts (onlyServer=qfalse)
at src/common/scripts.c:3355
type = 0x94b77c0 <headerType.8245> "window"
name = 0x94b7800 <headerName.8246> "mailclient"
text = 0xac94e65 "\n\n\t// ", '=' <repeats 18 times>, "\n\t// text and info\n\t// ", '=' <repeats 18 times>, "\n\n\tstring mailclienthead\n\t{\n\t\tstring\t\t\"_Mailclient\"\n\t\tpos\t\t\t\"355 30\"\n\t\tsize\t\t\"290 30\"\n\t\tcontentalign\tALIGN_CC\n\t\tcolor\t\t\"0 .78 0 1\"\n\t\tfo"...
#19 0x080c43ef in Qcommon_Init (argc=10, argv=0xbffff2d4)
at src/common/common.c:1205
s = 0x9721260 <string.4410+28672> "pics/background/irc_bg_rm"
#20 0x08129cb3 in main (argc=10, argv=0xbffff2d4)
at src/ports/linux/linux_main.c:50
No locals.