|Norton is probably the problem, can you boot to safe mode and uninstall Norton?|
On my pc (Compaq) I tap F8 once every half second immediately after the Compaq splash screen disappears while the cursor flashes in the top left corner of the screen, then use the down arrow key to select option 3, safe mode and press enter.
It may be a different key, such as ctrl that you need to tap to enter the options screen to choose safe mode, then after Windows loads in safe mode, try to uninstall Norton via add/remove programs and reboot to normal mode if possible.
Then you'll probably need to download the Norton removal tool from the Symantec web site, get the one for the specific version of Norton you had installed and run the removal tool.
Then reboot again and download AntiVir PersonalEdition Classic or another free antivirus program like AVG or Avast and install it and run a scan.