Vista - Vista locking up!!!

This has happened recently and I don't know why its doing this, but whenever
I download a program and try to run it, my Windows Explorer completly locks
up for like 5 - 10 min, and then my program executes. Its odd cause I can do
everything else like hit my start button and load other things...Its just
when I extract files and try to run them that it does this.

I figured it was a virus, or that my computer just needs a general cleaning
so I decided to reinstall Vista. Well I did that twice now and it still does
the same thing! Its odd how it does it. Can any of you help me? Keep in mind
that its ever done this before until just a few days ago, so yes my computer
is capable of handling Vista.