Well he has clearly re-infected himself because the task manager issue is a known malware symptom that is frequently caused by Vundo variants.
So regardless of whether he was clean 2 weeks ago or not he's infected now and needs to clean the system again. He's not getting browser hijacks, he's got a piece of adware generating popups. Another known symptom of several Vundo variants.
To be honest he probably needs to take the machine to a professional or let someone he trusts remote in and fix the issue because there's a good chance it will require some specialized cleaning.