Looking for help with windows 7 64 bit

Having massive problems with my machine.
I normally help people fix their computers both for hardware or virus/malware related problems....But now I'm not even able to determine what's wrong with my machine. Hoping someone here can give me a clue or help me fix it...
Symptoms:
Using process explorer I can locate a svchost running a number of standard windows processes (see attached image). The problem is this svchost eats all my ram memory at first slowing the machine down to a near standstill. after a while the process settles a bit and I can run some programs although dreadfully slow. In the beginning of this phenomenon there was also some mad disk activity going on which have also settled. I seem to be unable to start any crucial system components ie msconfig, computer management, resource monitor.
I'm able to start the computer in safe mode and I've run some antivirus scans and have come up with nothing....can't seem to find any obviously suspicious processes so I'm hoping for some help....