memory could not be written error

hello, i keep getting an exe error, specifically for sgtray.exe, but it does happen for other exe files. The error says "the instruction at 0x0244bcef reference memory 0x00000000. The memory could not be written"
i scanned using spybot and ad aware and a virus scan, but the error still comes up alot and some functionality is gone, including playing videos. can you help?
thanks a lot