mmm i dont know much about computers but it could be some type of virus/spyware.
Best advise i can think of is to run a scan of your anti-virus programmes etc when your pc isnt connected to the internet.
If that doesnt come up with anything then open your windows tast manager (controll +alt + delete) and click on the processes tab. Then click on memory usage so the ones that use the most are ordered from the top.
Connect to the internet and watch closely for what appears near/at the top, and is stealing all your PCs memory/cpu.
Then you may find what is causing it, some programme other than the normal ones connected with the internet and help you to remove it.
Mabea google what appears(like randomprogramme.exe) to figure out what it is.
IF all else fails try a system restore from before the problem started.
As i said... i dont know much but i hope something helps![]()