Read this Post about Hoster 3.320, and then download and install it.
The problem is in 3.318 and 3.319, now fixed in 3.320.
We too thought we had a virus when we unknowingly lost files not related to Hoster at all. We are confident we found the code that along with Windows' random operations did the NTSF index damage. We are confident we have fixed the problem, but only you folks seeing the problem repeatedly can tell us it is fixed.
Thank you for your patience. We truly are sorry this happened, and believe we have solved it.