Cpu running 100% without any app running

Well considering its an older PC, it does not really surprise me that its running so much CPU power. You only have 1.5GB RAM and Win7 needs a good 2 GB minimum to run well. This mean your CPU need to constantly page files form your HDD to keep it running smoothly.

You recently loaded win7 on this machine right? You should have kept XP on the machine.

You could get some more RAM for it. That would help. If you can find DDR2 400MHz RAM. Its an ancient PC.

Hi  

Virus ???

All the best Brett  

Could be. But an antivirus would just do him worse.

Antivirus isn't going to run 100% when idle. Usually only flaky drivers or viruses do that. 2.8Ghz is slow for video editing, but not for general office work and web. The computer should still be near 0% when not doing anything.

Open up task manager and see what it says is running all the CPU.

Most anti-virus programs will try and do a daily scan now a days. Which means on an old machine like that not only could it take a while but it would easily use up 100% of the processing power while running in the background.

You need to look in the task manager and find out what is running as Twelve25 said.