Three possibilities come to mind:
1. Right-click on the My Computer icon on the Windows
desktop, left-click on Disconnect Network Drive, and disconnect
any mapped drives that are not currently available.
2. If you are using Symantec/Norton Antivirus, try disabling
the Office Plugin that comes with it. See
http://support.microsoft.com/?kbid=329820 "How to use Office
programs with the Norton AntiVirus Office plug-in" for more
information.
3. See
http://support.microsoft.com/?kbid=830561 "Documents
that have attached templates take a long time to open in Word
2002 and in Word 2003".