I attempt to open Sapien with the tutorial.scenario, it freezes as usual for a bit, works for about 3 seconds and then closes by itself.
Downloaded from Halomaps, in my Halo CE directory.

If you have a duo core processor set the affinity of it to 0.

If that doesn't work, post your debug here.

How would I do that?

Task manager. Right click on the process. Set affinity.

I've tried and I have the affinity set to two CPU's 0 and 1.

Debug

08.20.09 20:44:04 sapien pc 01.00.00.0609 ----------------------------------------------
08.20.09 20:44:04 reference function: _write_to_error_file
08.20.09 20:44:04 reference address: 401b13
08.20.09 20:44:04 Couldn't read map file './sapienbeta.map'
08.20.09 20:44:04 CreateDevice succeeded with refresh rate = 0
08.20.09 20:44:05 Sound card doesn't meet minimum hardware requirements. Disabling hardware option.
08.20.09 20:44:05 Increasing sound decompression buffer size to 1048576 bytes
08.20.09 20:44:23 local player 0, weapon (0x0), deleted unexpectedly
08.20.09 20:44:23 EAX: 0x00A27F68
08.20.09 20:44:23 EBX: 0xFFFFFF01
08.20.09 20:44:23 ECX: 0x000250D2
08.20.09 20:44:23 EDX: 0x0000000F
08.20.09 20:44:23 EDI: 0x0012F300
08.20.09 20:44:23 ESI: 0x00000000
08.20.09 20:44:23 EBP: 0x0012F1D8
08.20.09 20:44:23 ESP: 0x0012F1C8
08.20.09 20:44:23 EIP: 0x7C90E514, C3 8D A4 24 ?????
08.20.09 20:44:23 EXCEPTION halt in \halopc\haloce\source\cseries\profile.c,#442: parent_timesection->self_msec >= child_timesection->elapsed_msec

Try running as admin if on vista and set the compatability to windows 95/98.

Set it to only 1. So, that means unchecking one of them.

I've tried setting the siffinity to 1 and it still doesn't work.
I'm working on Windows XP.

Set it BEFORE opening a scenario. So this is what you'd do.

1) Open Sapien, but do NOT open a scenario.
2) Set the affinity
3) Apply
4) Open a scenario.

I've tried again and it still doesn't work.

Try reinstalling by downloading the full HEK.
Run it as an administrator and make sure you have the windows classic theme enabled.
Sapien has problems running with themes activated on both XP and Vista.
If that doesn't work well than im sorry i have no clue what to say.

Sorry if this doesn't help.

I've tried all of these.
When I changed to classic, and the affinity to 0, Sapien lasts for about 5 minutes then crashes.

Check the debug then. Do you have the same error?

08.23.09 16:38:28 sapien pc 01.00.00.0609 ----------------------------------------------
08.23.09 16:38:28 reference function: _write_to_error_file
08.23.09 16:38:28 reference address: 401b13
08.23.09 16:38:28 Couldn't read map file './sapienbeta.map'
08.23.09 16:38:28 CreateDevice succeeded with refresh rate = 0
08.23.09 16:38:28 Sound card doesn't meet minimum hardware requirements. Disabling hardware option.
08.23.09 16:38:29 Increasing sound decompression buffer size to 1048576 bytes
08.23.09 16:38:32 local player 0, weapon (0x0), deleted unexpectedly
08.23.09 16:38:33 EAX: 0x00A27F68
08.23.09 16:38:33 EBX: 0xFFFFFF01
08.23.09 16:38:33 ECX: 0x00000AB5
08.23.09 16:38:33 EDX: 0x00000029
08.23.09 16:38:33 EDI: 0x0012F300
08.23.09 16:38:33 ESI: 0x00000000
08.23.09 16:38:33 EBP: 0x0012F1D8
08.23.09 16:38:33 ESP: 0x0012F1C8
08.23.09 16:38:33 EIP: 0x7C90E514, C3 8D A4 24 ?????
08.23.09 16:38:33 EXCEPTION halt in \halopc\haloce\source\cseries\profile.c,#442: parent_timesection->self_msec >= child_timesection->elapsed_msec

Set the compatibility of the program to windows 98, see if that works.