Hard Drive Full?

Is it showing the disk as being 500gb total? Might be an issue with the computer not recognizing the entire drive. (its ok if its somewhere in the neighborhood of 500, they won't usually read exact size)

Also check for hidden or system files/folders.

Have you checked all subfolders?

 

download and run windirstat - gives you a visual representation of the types of files and you can see what might be eating all that space. Perhaps you have a huge stash of NSFW stuff on there, hidden?

 

I think this could be a virus issue, I would try running a scan.

 

Doubtful, very very doubtful. Viruses do damage, they don't fill up your drive. Viruses can make systems unusable, which isn't happening much these days because it isn't profitable. However, if you feel it is malware, that could be a possibility, a small possibility where your computer could be a drone computer being used out there to store who knows what.

An example to frighten employees where I work as to how certain insecure systems can be utilized - they can basically be hacked, and used as child porn servers to distribute child porn on distributed hacked servers out there where the originator of the site doesn't have any liability since the pictures are not technically on his server, but some random user or random company.