The feature your referring to is the compressed file scanning. Compressed file scanning will give a dialog in the bottom corner when a scan is taking some time and the application is waiting for it to complete.
To disable Auto-Protect compressed file scanning :
Start NAV. If NAV is installed as part of Norton Internet Security (NIS) or Norton SystemWorks (NSW), then start NIS or NSW.
Click Options. If you see a menu, click Norton AntiVirus.
In the right pane, under "Which file types to scan for viruses," click to uncheck "Scan within compressed files."
Click OK.
If this does not fix the problem, then re-enable "Scan within compressed files" and continue on to the next section.