My Sansa c250 won't charge properly.\r\n

My Sansa c250 won't charge properly.
Initially when I bought it, I used it with a Windows XP PC, no sweat. That computer died and I began charging it with an OSX instead. It worked for a while, but after a time it wasn't getting a charge. I tried plugging it into other computers with XP (not mine), even got a wall charger and new battery and it still doesn't charge.

With the new battery and using the wall charger, I plug it in and initially it does charge, but after a short time (~10 seconds) it switches to the synchronizing screen instead, even though it is not connected to any computer.

Is there any way I can correct this proplem without using a computer or taking all the songs off?