or path indicated?
I checked several sites via Google (malware +runtime packed fsg)
found many such questions without a very clear answer. Included also posts where the files were legit and "packed" by the user for extra security.
Many "protectors" it seems are unable to open & view the contents of such so either claim a malware hit or possibly (better) will simply report it's there to bring to your attention.
Note: Some legit security programs (SAS etc.) may use similar to safely lock up parts of their programs or their quarantines to keep them safe from malware attacks/corruption.
IF you have the full name & path, you could try to locate it and copy it and submit to Virus total for analysis by about 30 different scanners at once and see the average result...(keeping the above in mind). Virus Total will scan multi-files to a total size & Jotti will scan single files only. Good Luck!
How dangerous is "runtime packed fsg" and what does it do ?
Know one on the avg forum knows how to answer this.