Vista: Windows Explorer stops working

Just installed on my home PC.  When I open Explorer it doesn't immediately show the files and the green indicator at the top of the explorer window is moving as if it's working on finding something.  When I try to move a file it just gets stuck.  Sometimes, when I open Explorer all I get is a blank white window with nothing in it.

 

I uninstalled NIS and everything works again.  Any ideas? 

 

Thanks.