I'm trying to run Blender under Linux, but I'm unable to do that, whenever I try I get some errors. I'm using Kubuntu 12.04 with KDE 4.11.1.

This is my video card:

~$ lspci | grep VGA
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV610/M74 [Mobility Radeon HD 2400 XT]

I used to have installed the fglrx proprietary Catalyst drivers, but lately they gave me some system-wide problems and I had to revert to the open source Mesa drivers (I don't think that these details are important, but just in case, the whole story is here).
Whit the fglrx drivers Blender was running fine, but now, whenever I try to start it, I get this error message (some parts are in italian, but I think that they are easily understandable):

~$ blender
connect failed: No such file or directory
Writing: /tmp/blender.crash.txt
Errore di segmentazione (core dump creato)

The content of /tmp/blender.crash.txt is as follows:

# Blender 2.68 (sub 5), Revision: 60150

# backtrace
/usr/lib/blender/blender() [0x877a41f]
[0xb7756400]
/usr/lib/i386-linux-gnu/libLLVM-3.0.so.1(_ZN4llvm3ARM8SPRClassC1Ev+0x15) [0xa8f4a9d5]
/usr/lib/i386-linux-gnu/libLLVM-3.0.so.1(+0x25ca48) [0xa8eefa48]
/lib/ld-linux.so.2(+0xeeab) [0xb7765eab]
/lib/ld-linux.so.2(+0xef94) [0xb7765f94]
/lib/ld-linux.so.2(+0x12fa6) [0xb7769fa6]
/lib/ld-linux.so.2(+0xeccf) [0xb7765ccf]
/lib/ld-linux.so.2(+0x127f4) [0xb77697f4]
/lib/i386-linux-gnu/libdl.so.2(+0xbe9) [0xb4ff9be9]
/lib/ld-linux.so.2(+0xeccf) [0xb7765ccf]
/lib/i386-linux-gnu/libdl.so.2(+0x133a) [0xb4ffa33a]
/lib/i386-linux-gnu/libdl.so.2(dlopen+0x47) [0xb4ff9c97]
/usr/lib/i386-linux-gnu/mesa/libGL.so.1(+0x3cbf0) [0xb7717bf0]
/usr/lib/i386-linux-gnu/mesa/libGL.so.1(+0x4079d) [0xb771b79d]
/usr/lib/i386-linux-gnu/mesa/libGL.so.1(+0x1a3aa) [0xb76f53aa]
/usr/lib/i386-linux-gnu/mesa/libGL.so.1(glXQueryVersion+0x2e) [0xb76f0cee]
/usr/lib/blender/blender(_ZN15GHOST_WindowX11C1EP15GHOST_SystemX11P9_XDisplayRK10STR_Stringiijj18GHOST_TWindowStatei25GHOST_TDrawingContextTypebbt+0x11c) [0x8f54aec]
/usr/lib/blender/blender(_ZN15GHOST_SystemX1112createWindowERK10STR_Stringiijj18GHOST_TWindowState25GHOST_TDrawingContextTypebbti+0xd7) [0x8f4f4a7]
/usr/lib/blender/blender(GHOST_CreateWindow+0xb6) [0x8f4cf86]
/usr/lib/blender/blender(wm_window_add_ghostwindows+0x205) [0x8799be5]
/usr/lib/blender/blender(WM_check+0x50) [0x877b670]
/usr/lib/blender/blender(wm_homefile_read+0x111) [0x87859f1]
/usr/lib/blender/blender(WM_init+0xd2) [0x8787872]
/usr/lib/blender/blender(main+0xe6e) [0x873848e]
/lib/i386-linux-gnu/libc.so.6(__libc_start_main+0xf3) [0xb4e694d3]
/usr/lib/blender/blender() [0x8778a99]

The only thing that I can guess from this report is that the mesa drivers are somewhat involved, as I already suspected, but I don't have a clue on what I need to do to try to solve the issue.