For what it's worth: I originally experienced the problem using the default kernel -- 2.6.28-11-generic. Booting an older kernel -- 2.6.27-11-generic -- didn't help.
For what it's worth: I originally experienced the problem using the default kernel -- 2.6.28-11-generic. Booting an older kernel -- 2.6.27-11-generic -- didn't help.