http://free.avg.com/us-en/faq.tpl-crp.num-1325
If you need to exclude a certain "Potentially unwanted program" from any detection by AVG Free (for example if you are using an Ad-sponsored program or utility, which could be dangerous, but could also be used with your knowledge), you can exclude it from AVG Free Resident Shield and AVG Free tests detection this way:
These exceptions can be used for "Potentially unwanted programs" only. If you set the exception for a viral file (Trojan horse, I-Worm, Worm, W32...), this file will be still detected by AVG Free tests and the AVG Free Resident Shield.
These exceptions are not used for the AVG Free Email Scanner.
Note: The exceptions can be created for files only, not for folders.