My antivirus vanished after I updated it. Asked for a restart after update and when I restarted windows, Avast was no longer there. Tried talking to support but they were no help to me. I did get an error message saying a dll file was missing. After getting no where with support tried using my own head. I deleted avast did a reinstall and ran a virus check. There was a virus. So my problem is when avast is running everything slows right down. cpu is up to a 100 percent and when I go to task manager it say avast is using 95 percent of cpu. Does this makes sense? I have defragged and did all the things suggested. Any help will be really appreciated. I have a dell insperon 1525 4 years old but hardrive is 3 years old.