I’m running the Malwarebytes scan at present, which will likely take some time to do. I had some difficulty getting it started, receiving the same types of error messages I get with looking at so many webpages (i.e. “page is not responding”).
Have seen that with XP when something is eating up a bunch of processor time or memory problems.
I am assuming you're running Win 7 since you said the machine is less than 2 years old.