something is using over 50% of my processor

[kitbag]

for some reason explorer.exe is running at over 50%. When I open task manager its the only thing using anything of note. If i kill the process and restart it it goes back to 0, however when I open "my computer" and start to browse file on the C: drive it goes back to running at over 50% this then slows the computer down and makes file browsing impossible.

I have run ad-aware, spybot S&D, and AVG virus but they don't detect anything,

Does anyone have any ideas on this?

I do download shared sources like bear share but always scan before opening.

I have booted into safe mode and it's still the same there.

[kitbag]

Sorted it

Don't know how but an .avi file wouldn't delete as i thought i'd delete everything in my download file. it said it was being used by a program and to close all programs that could be using it.

I tried but it still wouldn't delete so i thought it may be explorer.exe that was using it as it was the only thing running that could.

so I went to command prompt and deleted it with the dos delete. this worked and now my processor is not working overtime.