I recently purchased two 8G clip+'s, I upgraded both to the current firmware on the day of purchase (just a few days ago).
Both are experiencing lockups just after large song uploads (during the refresh period).
Even after reboot, the lock up continues (once it reachs the refresh period), only deleting all the songs and reformatting will return the unit to operation. Of course once the songs are reloaded it will lock up again.
The lockups occur after a large upload (30+ songs), or any time the device is more that a third full.
I’m using the USB file system method for uploading.