Have you even run into a problem in AutoCAD (or a vertical such as Civil 3D), that you can't figure out such as a drawing behaving strange, commands not acting right, commands not working, or maybe even the whole application just won't launch? One of the first things I would suggest is to have someone new log onto your machine and launch AutoCAD under their Windows profile, essentially creating a new "AutoCAD Windows Profile". If the problem goes away when you do this, then it is probably some error or corruption in your own "AutoCAD Windows Profile".
Shaan Hurley has always been my reference for AutoCAD history and has an excellent page on this. So the question came up the other day "What was the first version of AutoCAD for Windows". My memory told me it was Release 12, but I was not quite sure. A little searching turned up this document which confirms that R12c3 (Release 12, patch c3) was the first major release for Windows (see first comment below regarding R11 for Windows). Since Windows itself taxed most affordable computer systems back then, most people probably stayed on DOS, Solaris, or one of the other platforms for AutoCAD at that time.
Are you missing the "Run" option on the Start menu in Windows 7? It is not there by default, although you can still use the "Win+R" key combination to launch the Run dialog. If you want to restore the Start Menu "Run" item, follow along....
Right click on the Start Button , choose Properties.
On the dialog that opens, select the Start Menu tab, and then pick the Customize button.
On the dialog that opens, scroll down until you see the Run toggle, and check it on.
Press OK, and OK, and now when you left-click the start menu, the Run option will be there
If you want to disable the annoying Restart Now or Restart Later dialog that pops up every 10 minutes after Windows automatic updates downloads and installs an update....without restarting Windows right then... take a look at this post.