Are you using Spysweeper 5.x with AV and, if so, is the AV activated? It is not wise to run two or more AV products in the same O/S.
Otherwise, you will need to turn off the appropriate shields in Spysweeper to eliminate this conflict. You can still schedule Spysweeper to run a full scan periodically to detect spyware.
I have heard that Norton 2007 insists on the removal of Spysweeper and Zonealarm before installing.