Just to jump on the overheating bandwagon - the CPU is a likely cuplrit - check for dust/fluff in the fins of the CPU heatsink - the fan may be fine (the intel supplied ones last a long time) but the aitflow poor because of crud in the heatsink.

Couple of other places to check:
Power supply - these typically have cheap fans that crap out fairly quickly
Video card - if it has a fan make sure it isn't too hot
RAM - usually cooled by air from the CPU heatsink
CPU on board power supply - Electrolytic capacitors may overheat and dry out - often accompanied by swelling or splitting at the vents of the can.

Don't forget, you computer is probably the best air filter ever built... They seem to attract every bit of dust in the room.

I would also use a second, or even third anti malware utility just to be certain. Malwarebytes is high on our list of usefull tools.

--=-- My credo: If it's worth doing, it's worth overdoing - just ask my missus, she'll tell ya laugh --=--
You're only paranoid if you're wrong!