Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
after your pc is up and running you can check doing
it will opens Windows Task Manager
You should go to the Processes Tab and review the list looking for any process taking and oversized amount of Memory. then copy the name of this process on your browser and then you will know if it is a virus/worm or not. if non of the processes show this behavior your problem may be that RAM memory is damaged or unsufficient. this requires hardware check.
Added after 2 minutes:
you can also make a virus scanning (if you don't have an antivirus yet i recommend avast.com -it is free)