I tend to base my decisions on what I either know or feel...that's the way that I decide my courses of action.
If I thought my system was infected beyond my ability to deal with it...I'd post in the AII forum and follow their instructions, no matter how long it took. Or I would delete everything and do a clean install of XP.
If I developed a system problem of some sort...I'd spend 3 days (at the most) working on it myself...and then I'd do a clean install
. Fortunately, I usually solve my own fiascos, but there have been some clean installs
Seriously, if you think it's a malware situation...I suggest treating it like one. If not, act accordingly.
I will say...I am of the personal opinion that a very large number of cases presented as "Windows/system problems" are, in truth, malware problems. I get the feeling that users usally know this, but try to pretend that it can be solved by some technique that does not include visiting the appropriate forum. I fail to see what's gained by this behavior, but then again...I don't understand a great deal which is done by human beings.