win xp pro start problem

i have win xp pro..a week back when i ran spy terminator(with clam win anti virus package)-it showed up norton anti virus file as a threat..novice that i am deleted it!!afterwhich i was trying to install avg anti virus free version but failed..my computer hung..so when i restarted it stops at the 'welcome' page n does not move forward though it goes to 'administrator/owner' page but when i press owner it reverts to the same sequence.
i am able to use the safe mode method..when i tried scans for disk,virus,spyware etc..it is clean.still the problem of booting in normal mode exists.can somebody help?thanks.
jois