Windows 98 not shutting down

In fact I have a compaq pressario 5636 with it’s orginal windows of compaq ,last time I installed Norton Antivirus 2001 ,after the installation I shut down the system and instead of shutting down it remain on its screen windows is shutting down andit stayed here till morning how should I correct this problem. I even removed that antivirus but still it refuses to shut ,so What should I do .