This happened when trying to save my game. I was playing as France, and it was still 1069: all I had done was send the king's brother as a fosterling to a different court, fought a minor war with a rebellious vassal of a vassal, married Agnes d'Aquitaine and gotten a rivalry with her father.
The exact text is as follows:
######## EXCEPTION: 0xC0000005 at address: 0x004C6A65: ACCESS VIOLATION read attempt to address 0x00000000
10/23/07 19:52:57
######## EXCEPTION: 0xC0000005 at address: 0x004C6A65: ACCESS VIOLATION read attempt to address 0x00000000
10/23/07 19:54:54
######## EXCEPTION: 0xC0000005 at address: 0x00408A91: ACCESS VIOLATION read attempt to address 0x09177F58
10/23/07 20:04:47
######## EXCEPTION: 0xC0000005 at address: 0x00602540: ACCESS VIOLATION read attempt to address 0x0000000C
10/23/07 20:29:58
SymGetLineFromAddr(): GetLastError = 126
SymGetLineFromAddr(): GetLastError = 126
I hope some fix is discovered soon.
EDIT:
I just loaded it again from an autosave, which was before the small war and the rivalry with Agnes' father. The game ran well until the king made a friend, then, just a few game days after, the computer froze and I had to restart it completely. I think I'm not going to start the game up again until a patch gets out there.
EDIT:
I am currently playing it again, this time with all programs usually running in the background (like virus scan, etc) shut off, as someone else had already done. It is currently stable - though I haven't done anything related to the ledger or the friends/rivals system yet.
EDIT: Having made a friend and a rival without crashing I can safely say I think the background programs were the culprit.
EDIT, YET AGAIN: But it came back when I tried to give a ducal title to someone who became my vassal after I took another (Not the same) ducal title from someone in a war.