Originally Posted by jdk2
On your phone, open the Browser, then BB button > Options > Cache Operations and clear everything.
You can also clear your caches from the Desktop Manager. To CLEAR all or just a particular cache. Go into Backup/Restore > Advanced
Scroll down on the right side until the desired cache is selected
Click on Clear. Back out of Advanced. Re-run the on Backup.
Either JDK2's way or the DM method should work.