I have AutoCAD 2005 installed on my Dell 8100 Inspiron notebook. I went to the Autodesk Website and downloaded Service Pack 1. When I installed Service Pack 1, I could no longer access AutoCAD. AutoCAD repeatedly displays the dialog box in which you have to enter the authorization/serial number. After entering the authorization/serial number AutoCAD states that the number is incorrect and again displays the dialog box. I can no longer open AutoCAD so I'll have to re-install it. The authorization/serial number I entered in the dialog box is the authorization/serial number with which I originally installed AutoCAD. Anyone know whats going on? Do I really need to install Service Pack 1?