We've had this problem mainly for users that we *upgraded* Office from 2003 to 2007. Our solution was this:
http://howtotroubleshoot.blogspot.com/2008/05/double-clicked-documents-slow-to-open.html Not sure if it will help you, but worth a try.
EDIT: Specifically, the following helped:
1.Go to Control Panel > Folder Options > File Types
2.Find and select Word Documents (DOC)
3.Click the Advanced button
4.Select Open in the Actions section
5.Click the Edit button
6.Uncheck "Use DDE"
7.Put your cursor on the "Application used to perform action:" box
8.Arrow all the way to the right and put in "%1" (include the quote marks)
9.If there is a /dde remove it
10.Click OK, then OK, then OK
11.Try to open another document