My Ubuntu 8.04 LTS server periodically has a high load avg spike(once every 2 days) resulting in Apache timing out and virtualy everything even SSH to the server is not possible. When I am on the console and run TOP is see that The load avg increases from less than 1 to above 60 in 15 mins.

How can I isolate the cause? top - 09:21:51 up 37 days, 20:18, 6 users, load average: 5.41, 5.53, 5.36 Tasks: 160 total, 2 running, 156 sleeping, 0 stopped, 2 zombie Cpu(s): 65.0%us, 8.8%sy, 0.0%ni, 1.0%id,24.6%wa, 0.3%hi, 0.3%si, 0.0%st Mem: 3989468k total, 3444984k used, 544484k free, 360460k buffers Swap: 11687248k total, 178168k used, 11509080k free, 881772k cached