Here's a proven example of what a bad hard drive can do, it was technically functioning OKin a RAID array but the system became extremely low and the load become high and IOWAIT was even higher and I always thought it was a bad application. The truth is that this failing 1TBHitachi has slowly gotten worse and caused huge slowdowns, (eg. 100% load on Thunderbird waiting for e-mails to load etc..). After swapping it out, tabs change instantly, emails are not lagged, and........
I'm running Ubuntu 10.10 with Asus NVIDIA GT430
2.6.35-32-generic-pae #65-Ubuntu SMP Tue Jan 24 14:06:16 UTC 2012 i686 GNU/Linux
Nvidia binary driver: 260.19.06
The screen sometimes completely freezes and locks up or everything starts going very slow:
[1903398.100007] NVRM: os_schedule: Attempted to yield the CPU while in atomic or interrupt context
[1903402.373210] NVRM: Xid (0001:00): 53, CMDre 00000000 00000080 00000000 00000005 00........