At this point, you're better off investigating the actual cause of the crashes and not going on speculation.
If the OS is corrupt or infected, you'll only be mirroring the problems x2.
You are pushing the limits on the c: drive's capacity, which can cause problems, but you should start by cleaning it up first to see if that's even why.
Remove what you don't use often and can re-install.
Burn or transfer large image or multi-media files and delete the originals.
Dump your temp files, scan for viri and malware, do the scandisk\defrag thing, etc, etc.
BTW, how many drives and partitions do you have? I see you're all the way down to K: in the alphabet.