Update to my freeze issue:

Called Sony tech support after MS tech support refused to help me.

Sony has no clue what the problem is. The best that they could give me is
that I might have to uninstall Vista & reinstall it after rolling back to XP
MCE. But there's no guarantee that that will work. Also, they wanted to
know if I could reproduce the freeze in Safe Mode w/Networking. I couldn't!
Is there anyone who CAN reproduce this freeze in Safe Mode w/Networking?

Correction to my earlier post: the freeze also happens regardless if i'm
using battery power or AC wall outlet. Looks like the only real solution may
be to permanently roll back to XP MCE. Did anyone else try anything that has
or hasn't worked?