This one is rough. My grandparents PC (ug right?) has XP SP3 on it. They have a genealogy program on it that installs to c:\legacy.
I did my usual cleanup with malware bytes and cc cleaner, as well as removed the dozen or so toolbars and useless programs that are inevitably on this type of box.
The problem they were having still persists. If I browse to c:\legacy and scroll down a bit my explorer.exe jumps to 100%. Keep in mind I'm not actually clicking or launching a thing. I can end it, restart it using new task run explorer and everything resumes normal performance. Odd thing is I can browse other folders perfectly fine. I can even start > run and open c:\legacy\data fiine. Heck I can even start > run to c:\legacy (as long as I don't scroll) everything is fine. As soon as I scroll down it jumps.
What possible mechanisms could be at play at this basic level? Nothing is being opened or even clicked on just a file list (detail view) displayed. Thought maybe it could be a virus scan, but MS Security Essentials is the only program they have, and it is still sitting at 0% CPU. I could understand if it were in thumbnail view or something, but this is detail view.
I'm honestly stumped and I've seen some odd stuff in my day, but I have no idea what OS mechanisms can even be at play here. Anecdotally they think it all started happening when they upgraded to IE8 in November, but I've already rest it to no avail.