THIS WORKED FOR ME ON WINDOWS 7 PROFESSIONAL BEAUTIFULLLY! ALTHOUGH I HAD NOT REGISTRY PROBLEMS, i WENT TO STEP #2 AND IT WORKED GREAT. RENAMED THE FILES AS INDICATED, REINSTALLED ILLUSTRATOR CS3, AND APPLIED THE TWO UPDATES MANUALLY SUCCESSFULLY. BEST PART, I DID NOT HAVE TO EXIT AND RESTART AND ANY TIME JUST LIKE HE STATED, FROM THE UNINSTALL TO RE-INSTALL, NO RESTART!
For Windows Vista users, check this link:
http://www.brianpeek.com/blog/archive/2007/11/29/weird-vista-registry- issue.aspx
I found I had that situation, which is a Microsoft problem, not adobe. Anyway,
1) I applied the solution there (better have a backup because you can easily toast your entire registry). Fortunately, that completed successfully - well, out of 150,000+ entries there was 1 entry failure but did not apply to the Illustrator update problem. (Oh, I had been getting the "registry not in the expected state" or whatever whenever I would start AI 13.0, tho' AI would still run).
So the registry fix above handled the registry situation. But the 13.0.1 and 13.0.2 updates still would not install. 13.0.1 started telling me that the updated had already been applied but Help>About said differently, i.e. still 13.0, and 13.0.02 update would not update.
2) So I then uninstalled AI only.
3) Then renamed the "Installers" and "Updater5" folders *only* in the c:\program files\common files\adobe folder. Didn't deleted them, just renamed them (e.g. the installer folder I renamed to "_installer" with an underscore in front of the name - same for "Updater5").
4) Then I ran the installer from the dvd, installing only AI 13.0.
5) After that completed I ran the 13.0.1 that I had manually downloaded onto the desktop. It installed without a hitch.
6) Likewise for 13.0.2.
I did *not* bother rebooting before, during, or after, *all* of the above.
The procedure also fixed a failed update to the Flash-Lite Device Central update that had just failed. All other updates to the CS3 products had never given a problem, just the AI and then, recently, the Device Central thing.
Hope this may be of some help to anyone running Vista who hasn't been able to update AI.