Why is my Microsoft Word window always on top of other windows?

Here's another answer I found online which doesn't require rebooting:

1. In Outlook go to Tools → Options
2. Switch to the "Mail Format" tab
3. Uncheck "Use Microsoft Office Word 2003 to edit e-mail messages"
4. Close Outlook and Word
5. Re-open Outlook and Word
6. In Outlook go to Tools → Options
7. Switch to the "Mail Format" tab
8. Re-check "Use Microsoft Office Word 2003 to edit e-mail messages"

It should now no longer be always on top.

I just upgraded from Office 2007 to Office 2010 on Windows 7 Professional Service Pack 1. When the Word document was open I could not open any other application in front of it.

I resolved the issue by going to Add-ins then Actions. I only had two enabled 1) Address 2) Instant Messaging Contacts. I disabled both of them.

This single-line AutoHotKey script can be used to toggle the always-on-top behavior of the current window whenever Windows-A is pressed:

#a:: Winset, Alwaysontop, , A