I have a home-built PC that has been running ffor some time now quite well. However, a few months ago after performing a routine disk clean-up and defragment the OS failed to start. The only way to fix this is to do a system restore via the start-up recovery part of the windows OS. If it is of any significance, avast found a rootkit in the C drive under Xaramin's software directory, under the name dynDNS.exe (I think but not sure, definitely had DNS in the name!). Could it be an infection causing this? Disk check was supposed to be launched during boot but I have seen no evidence of it happening. The full PC details are below: - AMD 8350 CPU - Gigabyte 7950 Radion HD graphics card - 16GB RAM dual channel at 1866mhz - Asus m5a99x motherboard - OCZ vertex 3 120GB SSD - Western Digital Green hard drive - Generaic CD drive - Windows 7 Pro 64-bit (virtualisation enabled via hotfix for bulldozer CPU's) Any ideas of why this could be happening? Also is any more information needed? Thanks guys!