You could always look in the AVG program folder and find the relative AVG.EXE file and rename it to XXAVG.EXE so that this operating file cannot be found by the system, consequently it may not operate correctly. Doing this may stop AVG from doing it's job, which is what you want for a short while.
If this is successful, you will have to remove the XX from the file name later and rename the file back to AVG.EXE (or whatever it was originally).
Hope this helps in some way.