Folks - there are scattered references all over the net regarding error message 1321 when attempting to update Adobe products. In my case, I was trying to update Acrobat Pro X. Most of the solutions involve changing security permissions in the various Adobe folders. This simply results in yet another 1321 error message for yet another Adobe program file: wash hands, repeat, ad nauseum.

One reference I found is to disable your antivirus software prior to running the update. In my case, I disabled Webroot, and was finally able to run the update successfully without any issues.