You will not be stepping on my toes I am sure that the OP will value any help and suggestions to improve the situation - so would II'll not step on Tony's toes....
Currently I am thinking that the "white box" is just a symptom of a corrupted system - maybe old dial up networking related or even a "dialler scam" application that has been inadvertently downloaded.
Anyway I think that the Task Manager issue should be a priority as well as the AV and Firewall issues.
EDIT: Just read Igorian's post - makes a lot of sense to me and in the long run may be a lot quicker than "farting about" trying to fix a broken system