Ask the maker of the antivirus how to test for that.
My Microsoft Office 2007 Home and Student Edition's "copy," "cut and paste" function has an irritating trait of having a delay before it will copy or cut, and the same delay for the paste. The delay can be as long as 10 to 20 seconds in a Word document, and even longer in Excel spreadsheets. Rarely, however, the function will, for no apparent reason, recover to its "normal" state of instant copy, cut, or paste. However, when the computer is restarted, it will resume the delay. I believe an occasional delay in closing documents may also be related to this overall problem.
Some other information may be helpful. I am using Windows 7, 64 bit, Ultimate Edition on a Dell Studio XPS 8100 computer. The problem started about 6 months after I got the computer. I do not consider myself expert, or even moderately so, in computer tech work.