Microsoft has released a patch (MS04-013)
specifically to resolve this problem.
You should also, update your Norton Virus definitions, and rerun the virus scan.
Also, it may be necessary to go into and modify your 'System Configuration Utility' and check to insure that your 'Startup' and 'System' configuration definitions have not been altered. to do this...
1. Click 'Start' and select the 'Run' option.
2. type msconfig
, and the 'System Configuration Utility' window will be displayed.
3. From here you should see the 'Startup' and 'System' and query them. Be sure to clear the boxes that do not belong to these lists.
If you are unsure what belongs and what doesn't, follow this link...
and it should help.
I don't know how computer savy you are, but you may need to locate the closest nerd and pay him/her to help you.
One other thing to consider would be to perform a 'System Restore' back to a point where your system was working. This last one is a long shot, but it's worked for me on many occasions.