I have a similar issue where I'll have a sudden freeze for a few seconds and then a reboot. This happened in the 32-bit version as well. This happens at least once a day. I ran Karmic for a while and it didn't seem to happen. Any help or advice is appreciated.
I'm on a MacBook Pro 2,2 as well:
2.6.32-21-generic #32-Ubuntu SMP Fri Apr 16 08:09:38 UTC 2010 x86_64 GNU/Linux
I have a similar issue where I'll have a sudden freeze for a few seconds and then a reboot. This happened in the 32-bit version as well. This happens at least once a day. I ran Karmic for a while and it didn't seem to happen. Any help or advice is appreciated.