It's probably spyware/adware/etc. and not a virus, especially due to the downloading. Your friend needs spyware/adware removal and blocking programs in addition to McAfee. Here are a few free ones.
Spybot S&D (download, check for updates, read the tutorial and scan often, it also does some blocking)
SpywareBlaster (a blocker only, download it, check for updates, enable it and leave it alone except for checking for updates occasionally)
SpywareGuard (similiar to SpywareBlaster but works in a different way and does not update as often for that reason.
Ad-Aware SE (a scanner, download, check for updates, read the directions and scan.
cwshredder (stand alone unit)(another small scanner for certain things, ALL other windows should be closed)
I was asked to look at a neighbours computer yesterday. It is an Advent brand with a Pentium IV processor and 256Mb of R.A.M running XP Home with SP2 installed.Hardware all running ok. Anti-Virus is McAfee (2003 edition)which revealed nothing on a scan he said. He has had the system around nine months without any problems.
Two weeks ago performance began to decline this was particularly noticable at initial start up/ shut down of Windows, boot performance appeared normal to me up until this point. Then his toolbar at the bottom of the screen disappeared.He said he had tried System restore and defragment had with no effect.
Among other strange happenings was although I could access Computer Properties / system restore (after a very long wait - say 15 minutes) It would not allow me to turn off system restore to initiate some recovery processes (I had decided the most probable cause was malware/virus by this point having run a number of diagnostics and been there over six hours) .
In the end we did a standard system recovery with the recovery disk but the problem persisted (which did not surprise me) so we ended up doing a reformat and recovery which seems to have provided a (temporary I suspect) solution.
He does download quite a bit and recently dowloaded updates to RealPlayer - which I have known to cause problems sometimes. Also he has downloaded various thing from websites of unknown provenance.
Has anyone else experienced similar symptoms with XP recently? I am wondering if this was a new virus or whether it was simply not detected because of the version of McAfee being rather old, or if it was a virus at all but some software conflict.
I am very sorry for such a long post but I am really intrigued as to any possibilities.
Thanks in advance