Check Trend Micro if you're losing space on C:

As many of you are aware I love using Trend Micro for A/V on the SBS platform. It works, it's efficient, the client updating could use a little tweaking but hey nothings perfect! Recently we had a client who's C: was getting sucked drier than a pond in Arizona during summer. The culprit? Trend's A/V quarantine function.

By default Trend quarantines all virus' and information to the C:\Program Files\Trend Micro\OfficeScan\PCCSRV\Virus directory. When we checked that directory the client had over 9.9GB of space in that directory alone. Cleaned it up and we were good to go. On the client side options we made sure to delete or clean the virus first rather than quarantine so as to avoid the situation again.

It's the little things that get you. Of course if this client had not been on a maintenance plan with us they would have cried sooner rather than later about everything shutting down due to a lack of space. This is where having a bona fide maintenance plan with your IT provider can really pay in the long run.