Same on openSUSE 11.3
sometimes this leads to a complete freeze, where only the mouse cursor can be moved, but the rest of the display does not react.
Additional in /var/log/messages there is:
NVRM: Xid (0001:00): 8, Channel 0000007e
NVRM: Xid (0001:00): 13, 0003 00000000 00000000 00000000 00000000 00000001
which occurs several times
Driver was installed through .sh from nvidia homepage