In fact, I don't have much programs on my BB. I wonder what's going on with that error message. I tried to install other programs and they work. I tried to install the Yahoo! To Go, and it failed (and showed the error msg as the one from the first post).
-- TMO Blackberry 8700g since 09/24/2006
Try not backing up the device during software updating. There should be an option to automatically back up data and apps, and one to not. You should still manually back up so you don't lose data though.