I have a dell computer with a 3 years warranty. if i open it up, then i void the warranty. How can I clean out the dust, if I can’t open it up?

The thing is my computer was infected by a pif virus named igef.pif i reinstalled my os. Eventually the virus was gone, but after i installed or run any software from my local drives the virus was re generated. I found that every exe files in my pc was modified by the virus. my anti virus deletes the virus form the windows but i couldn’t repair the exe files. so if any one knows the solution plz help me out!!

my internet explorer homepage cannot be changed too.is there anything i can do about that

I have a progrem that I’m not able to uninstall, where can I found a registry cleaner to help me out.