Bob
Bob
No need to save anything from Illustrator unless you have certain preferences that can't easily be recreated. In the case of special preferences, then you'd want to save AIPrefs file (do a FIND for it, as each operating system saves it to different path. Be sure to allow FIND to view HIDDEN files, as AIPrefs would otherwise not be found.
If you have special Brushes or swatches you've created and saved for new layouts, you'd want to save your "Adobe Illustrator Startup_CMYK.ai" file and "Adobe Illustrator Startup_RGB.ai" file. You'll find these files in your PlugIns folder.
Other than that, just be sure after uninstalling that you manually remove any files/folders the uninstall didn't remove from Illustrator (usually the case). Then do a clean reinstall and especially do not have anything from Norton or your anti-virus program active when you install. See if that fixes things.
Bob