HI,

This is not uncommon, do you have a firewall or virus software? If so, manually stop these before shutting down. Mcafee in particular can cause this problem. You may also have to shut down related processes manually in task manager.

It's interesting that the problem is still there after a reformat, was the problem there before you installed any apps or drivers? If so this could be a problem with you HDD, or more likely your CD.

I hope this is of some help
phill