Not sure why you put the word virus in your thread but heres some tips for you
With regards to pc protection i dont have widows defender running in the background but i do use it once a week. I used to reboot my pc to a never used state once a year but several years ago i could not re-install some disc based games because the piracy check systems were saying they were already in use ..... yes they were by me !!!
If you are refering to cleaning as in dust then use something called an air duster its air in a can. Turn pc off and remove the side panel. VERY IMPORTANT ...... keep the can vertical at all times or the propellant will squirt out. Get the cold air version and only use in short bursts because the can will suddenly become very cold and burn your fingers.
If you think you have a problem then work your way through the list below.
1. run dxdiag
2. run windows memory test , it will tell you if ram is faulty but not which stick
3. check device manager for any yellow triangles.
4. use task manager to see what is running in background.
5. look in add/remove for anything you dont recognise.
6 look in reliability monitor and google any errors.
7. run scans with malware bytes , anti virus and widows defender , all 3 look for different things.
8.keep all drivers up to date.
NOTE ... if malwarebytes finds anything , quarentine and delete it and run scan again till it finds nothing , the is necessary because malware stuff can be in several segments and malwarebytes does not always get rid of things on first scan