I had the same problem as did many others using all BB models. The problem is a corrupted browser cache. A work around is to go to advanced in the desktop software when backing up, and select all the files on the right, BUT DO NOT select the browser cache. Then hit the arrow pointing to the left side pane. It will copy all the files over to your computer. Then look above that left pain where you can choose "file/save as" and save the backup to wherever you want.
I had the same problem as did many others using all BB models. The problem is a corrupted browser cache. A work around is to go to advanced in the desktop software when backing up, and select all the files on the right, BUT DO NOT select the browser cache. Then hit the arrow pointing to the left side pane. It will copy all the files over to your computer. Then look above that left pain where you can choose "file/save as" and save the backup to wherever you want.
Couldn't you also just clean out your browser cache?