My laptop freezes with anything above driver 7676, no error messages..
My laptop is a toshiba 5205 s503 with a GeForce 4 Go 460.
The only suspicious thing I've found in the logs (/var/log says nothing, no kernel panic messages, etc) are these messages in the Xorg.0.log:
(==) NVIDIA(0): Write-combining range (0xfd680000,0x1000) was already clear
(==) NVIDIA(0): Write-combining range (0xfd601000,0x1000) was already clear
(==) NVIDIA(0): Write-combining range (0xfd682000,0x1000) was already clear
(==) NVIDIA(0): Write-combining range (0xfd603000,0x1000) was already clear
Other than that, no error message whatsoever.
This behavior is identical in the linux nvidia driver (I tried it while using Ubuntu breezy badger), so it's not likely to be FreeBSD's fault...
I *suspect* maybe some kind of acceleration was enabled by default in drivers above 7667 which my laptop does not support (for example, in the current driver, enabling xrender, composite and using xcompmgr freezes it almost instantly).