Try using Process Hacker (http://processhacker.sourceforge.net/) it's way better than the default task manager and it shows some hidden processes. And if it doesn't show, chances are you may have got rooted by some Malware.
I found this with a quick Google search (unknown process h -process.h -windows.h)
http://spyware.scanspyware.net/spyware-rem...wn+process.html
Which has C:\Documents and Settings\user-account-name\Local Settings\Temp\H.exe in its unknown Processes List
If I were you,
I'll BFIR for sure. (it's easier for me as I also have Linux on my hdd and also on my usb )