Network Share Freezing With Office 2003

Hi all,. this is my first post so i hope that i am in the right section.i have a really weird problem tha i have never come across before. basically we have taken over a new companys network. after installing there new server and mapping there files to network drive maps everything seems ok exept when i try to load office document such as word, excel ect it hangs from anywhere between 10 seconds and 5 minutes.i havnt slept yet as they need there network up and running. i have tried literally everything. they are running HP printers and a HP scanner. i have tried the HP scan to web fix and still nothing.

any advice would be great

Ashley