First some relevant specifications of my system. Gentoo Linux with mixed 32bit 64bit libraries, kernel is gentoo-sources-2.6.23-r2, mono-1.2.5.1-r1, libsdl-1.2.12, glibc-2.7 with debugging sybmols.

Now the output of my program, which ran on a different system("entering .run" is still desired output"):
mono sauwetter.exe
Please enter a filename
/home/benjamin/table.obj
Entered constructor of Mesh
File has 2566 lines.
reading in vertices finished.
857
reading in faces finished.
Please enter a filename
/home/benjamin/table.obj
Entered constructor of Mesh
File has 2566 lines.
reading in vertices finished.
857
reading in faces finished.
entering .run
Stacktrace:

at (wrapper managed-to-native) Tao.Sdl.Sdl.SDL_MapRGBA (intptr,byte,byte,byte,byte) <0x0000e>
at (wrapper managed-to-native) Tao.Sdl.Sdl.SDL_MapRGBA (intptr,byte,byte,byte,byte) <0xffffffff>
at SdlDotNet.Graphics.Surface.GetColorValue (System.Drawing.Color) <0x0011c>
at SdlDotNet.Graphics.Surface.Fill (System.Drawing.Rectangle,System.Drawing.Color) <0x00096>
at SdlDotNet.Graphics.Surface.Fill (System.Drawing.Color) <0x00121>
at com.arsfides.sauwetter.Application.Tick (object,SdlDotNet.Core.TickEventArgs) <0x00059>
at SdlDotNet.Core.Events.OnTick (SdlDotNet.Core.TickEventArgs) <0x0003e>
at SdlDotNet.Core.Events.ThreadTicker () <0x000da>
at SdlDotNet.Core.Events.Run () <0x0002a>
at com.arsfides.sauwetter.Application.Go () <0x00139>
at com.arsfides.sauwetter.Application.Main () <0x0002d>
at (wrapper runtime-invoke) com.arsfides.sauwetter.Application.runtime_invoke_void (object,intptr,intptr,intptr) <0xffffffff>

Native stacktrace:

mono [0x523c01]
mono [0x4f1d9d]
/lib/libpthread.so.0 [0x2aff45c69480]
/usr/lib/libSDL-1.2.so.0(SDL_MapRGBA+0) [0x2aaaabdd9050]

Debug info from gdb:

(no debugging symbols found)
Using host libthread_db library "/lib/libthread_db.so.1".
(no debugging symbols found)
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0x00002aff461b5932 in select () from /lib/libc.so.6

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================

Aborted

Edit: please leave a comment, when you've fixed the bug or have any questions.

Edit(2008.03.10): Works fine now on my Linux. I think the problem might have been that I didn't have all these dependencies:zlib, libpng, mpeg, and the lot.