theres also this, courtesy AVG Website
1215:Warning in a test result
The AVG test may report a warning - potentially dangerous object on some files, which may be infected or pose a potentional threat. Typical examples of such detection are hidden files, cookies, suspicious registry keys, password protected documents or archives, etc.
Warning does refer to a file that cannot be scanned (password-protected archive), or to potentially suspicious files (hidden files, cookies, etc.). Such files do not present any direct threat to your computer or security. Information about these files is generally useful in case there is an adware or spyware detected on your computer. If there are only Warnings detected by an AVG test, no action is necessary.
This is a brief description of the most common examples of such objects:
The hidden files are by default not visible in Windows, and some viruses or other threats may try to avoid their detection by storing their files with this attribute. If your AVG reports a hidden file which you suspect to be malicious, you can move it to your AVG Virus Vault and send it to us for analysis.
Cookies are plain-text files which are used by websites to store user-specific information, which is later used for loading custom website layout, pre-filling user name, etc. More information is available in the FAQ dedicated to this detection.
Suspicious registry keys
Some malware stores its information into Windows registry, to ensure it is loaded on startup or to extend its effect on the operating system.
Password protected documents or archives
Password protected files can not be scanned by AVG (or an Anti-Malware program in general), as explained in this FAQ topic.
If you wish, you can adjust the AVG test settings in such way, that only the warnings you are interested in are reported:
open AVG User Interface
click on Computer scanner
click "Change scan settings"
alternativelly, you can change these settings in menu Tools - Advanced settings
More information about the files detected by AVG is available in the FAQ section covering viruses.