xp logs me off as soon as I click on my acct

I am a newbie.
I am using xp media edition 2004, I think? this is considered xp pro
Dell pentium 4 3.0 HT
512
about 160 gigs, lots of space
I run AVG Free, Zone alarm, Spybot, adaware

recent activity included trying antivir and a free clock program tbc pro featured in PC World.

among the last legitimate uses of my computer I noticed the clock program disappeared, I reinstalled it. and possibly had run spycatcher.

When I turn on my computer it gets to the desktop with no icons visible yet then suddenly goes to the blue screen and expects me to click on myself Charles. when I do click it says logging off.
Please note, this is a legitimate, not stolen OS.
Please note, I googled the problem and it seems this activity is seen with a change to a line of the registry but I think I found that line or something like it c:\windows\system32\userinit.exe
seems to be intact.

I do not have recovery disks, I do have a recovery DVD that I was supposed to copy to CDs

 

have you tried booting into safe mode and see what happens?? i'd try that 1st (if you haven't), and post what it says etc. also, you might want to try last known good configuration? (i'm sure others will reply) - sos

 

If you do go into safemode you might try system restore and see if that helps.

 

Thank you for the reply.
Unfortunately, I have tried safe mode, reset to a previous saved time, reset to last known good configuration, all to the same result.

I also tried setting up a new user and then logged in as the new user, same result.