Ratchet & Clank Future: Tools of Destruction released this week, but some users are finding that they cannot start the game. The bug causes the game to think that the hard-drive is full when it attempts to install the game files.
Thankfully, the fix is easy and Insomniac says that adding or removing 500mb of data from the hard-drive.
So delete some demos or movies or download some new ones. 500mb should allow the game to install and play properly.