Question : cpu at 100%

My HP Pavilion 2.8 ghz with 512 meg ram and an 80 gig hard drive is driving me nuts! It started running slow and then crashing, I went to task manager and noticed that the cpu performance was at 100%. I closed all unnecessay programs, but it wouldn't go down. i restarted the system and it still is at 100%. please advise. I am running Zone Alarm Pro firewall and AVG  7.0 virus protection. I have a
spyware program PC Bugdoctor.

Answer : cpu at 100%

Figpop, I think you looked at the wrong column (probably memory usage), look again :). Try to kill from the task manager the process that is consumming all the CPU. If you can't, or if after the next reboot it consumes all the CPU again (which seems your case), then I recommend a good anti spyware like Ad-aware, and a good updated antivirus, like the free online Panda Activescan. Google will help you to find them.