Shutdown errors are the probably the most common probelms in Windows 98 and Windows ME. They occur for many reasons, and are often difficult to track down. The most comprehensive guide to troubleshooting shutdown problems can be found at http://www.aumha.org/a/shutdown.htm. Note that this site also has a section that deals specifically with shutdown problems in Windows ME. Post back if you can't find the solution at this site.

Steve