I had Adobe Reader 9.2 on my desktop running Vista Home Premium SP2. When I opened Reader and went to "help," and then selected "check for updates," the pop-up window that normally comes up and shows the progress of the update search would appear, but only for a few seconds, after which I would get an updater window that just says, "Update Failed." There is no error code, and no other message.
I was able to successfully download and install Reader 9.3.0 manually from the Adobe website, but the updater is behaving exactly the same way in 9.3. Again, I could manually download and install the patches for 9.3 (9.3.1, 9.3.2), but if I try to "check for updates" from within the program the updater runs for a couple of seconds and then fails.