I had an virus on my game and deleted it after I noticed it aftre I updated my game. Even though you remove a virus and check it with a highly trusted virus scanner/Remover, is it really gone?
Virus I got/Deleted: iNfEctION
Well ok, before I give you an answer, why are you using free models? The virus named 'iNfEctION' is common in free models that people use and can be found in copied games.
Before using a free model, check everything in it before using it. If you use a lamp for example and find no viruses in it, double check the script. Look at every line of code in the script and try scrolling as far right to ensure if anything exists in the right side. This is also a common trick to avoid using visible virus models, so make sure you scroll through the entire script for any sneaky viruses.
If you seriously need to use or want to use free models, make sure the scripts aren't hiding anything and if you can, check the ratings on it.
I suggest using the Kronos virus scanner plugin. Very useful.