High explorer.exe cpu usage when typing.

I've been getting this weird problem with my cpu usage. It jumps to around 30% and lags my computer when I type. I checked the task manager and it seems that explorer.exe is the culprit, I re-formatted my computer 2 times and I still have the same issue.
I tried installing Windows Vista and the problem seems to go away though, it only seems to happen with Windows 7. I pretty much tried everything I can think of and I'm at a loss on what to do next. Any help would be greatly appreciated.

bump. Could use some serious help with this. Thanks in advance.

Capt.Jack Sparrow said:

Hi there,

What security software are you using? Try to perform a Clean Boot How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7

Before this whole ordeal I had Avast installed. I tried uninstalling it and even did a re-format but I still had the same issue.

I also tried the clean boot but it didn't seem to work.

whs said:

It could also be a driver problem. Make a quick check with Process Explorer and see whether you have a lot of Deferred Procedure Calls (DPC). In PE you see it as 2nd or 3d entry. If you are under 1%, you are OK. 2 to 4% and higher would be a problem.

Then you can also run the Latency Checker. If that shows red bars, something is wrong. It might even tell you which driver is the culprit.

My DPC seems to be ok. The highest it would go up to is 0.30%. Is that good?

whs said:

0,3% is OK.

I just let the DPC latency checker run for an hour or so and I didn't get a single red bar. I'm pretty sure this isn't a driver-related issue.