Using XP.

Ran an online scan and detected several problems.

Downloaded Malwarebytes and the trial version of Avast. Ran Malwarebytes and removed problems, as identified. Clicked on Avast to scan, which I thought might take an hour or so, but Avast continues to run. I am at 5 hours and still running. If I click to terminate, Avast says that the computer will not be protected. Does Avast continuously run, cycling through the various protections?