file permission error - NIS09

In the last couple of days I have been getting  an error “word cannot complete the save due to a file permission error” when saving Word 2007 files. The problem is that the file is actually then deleted. I have been able to access the *.tmp file but unable to open it, I get a message 'the file is already in use by another application or user' and just can't open it. I have already lost two files and I am worried that I will lose more.

I have been using Word 2007 for at least a year now and had never had this problem.  I have in the last week upgraded my NIS to Norton Internet Security 2009 and since started getting had this problem.

I have read that it is a NIS issue, that it can be fixed by configuring the personal firewall settings and unchecking the” Protect Office document” option.  The problem I have is that I can’t find the Personal Firewall settings and the option to uncheck the “Protect Office Document”. Can anyone direct me in the right direction, I am using NIS 2009 or any suggestions as to how I can fix this problem asap?