I don't know whether any of you are experiencing this, but I know I was and some other people I talked to were aswell, so maybe it's a common thing.
When I was playing CM5, it kept crashing in the middle of matches loosing everything after my last save and screwing up my computer into needing a restart. It prettymuch made it unplayable, however, I think I have found a solution to the problem from the readme's and help sections on the CM site, so far it's all working for me again anyway.
1) Completely uninstall the game.
2) Make sure you have the latest drivers for your video card and that they work with Direct X 8.1
3) Clean out old temp (.TMP) files from the C
WINDOWS\TEMP or C
WINx\TEMP directory on your hard drive.
4) Run Disk Defragmenter and Scandisk.
5) Make sure Virtual Memory is turned on.
6) Make sure no antivirus softwear is doing anything besides sitting dormant while the game is loading.
7) Reinstall the game and see if this works.
It worked for me, thankgod, because I nearly took it back to the shops.