Word crashes whilst saving, conflict with NAS?

Hello, I am using Macbook Pro i7 with OS X 10.8. My office suite is 2011. When using word periodically, sometimes once an hour and sometimes every save, a message comes up saying 'You cannot save while the file is in use by another process. Try saving the file with a new name' this changes the original file that i was working on to a Work File_2.tmp and forces me to save as a new name. All main files are saved on the Macbook and i do use timemachine to the ready NAS Duo.

Sometimes it won't even let me save to a new name and looses everything since the last recoverable save or spare backup I have made. The tmp file can also not be deleted, unless i restart the computer in which case it sometimes will open and other times comes up saying -43 code error.

I do not use citation as I have read this can cause the fault, I have ran all available updates.

From responses I have had on the Microsoft support website (link below) it is directing as a fault towards ready NAS i don't know how and any help will gratefully received

http://answers.microsoft.com/en-us/mac/forum/macoffice2011-macword/word-crashes-whilst-saving-and-changes-original/c061fbbc-5d10-4089-bb2d-b4bb53f627af

Please help!

Thank you, Mark