Zen sleek 20Gb

Hi, I had the same problem with my Zen Sleek. The problem turned out to be caused by a loose connection to the hard drive. I opened up the device, and saw that the cable was loose, so I attached it firmly, put it back together and all was well again. To take it apart; First peel off the front panel - the one with the slider and buttons. It's only glued on, it should come off easily. Then using a knife or small screwdriver, pop off the end panel - the one where you connect the cable to the pc, not the one with the power button. When this comes off you will see a silver panel held in place by two tiny screws - philips-head type. Unscrew these and this panel will come off, and the whole device should slide out easily. Now that you have it out of the shell, it should be pretty easy. The slim silver piece attached to the green circuit board by two wires, one red and one black, is the battery. Make sure it's firmly connected. The other thing, probably surrounded by blue plastic and with an orange cable connecting it to the circuit board, is the hard drive. In my case this was loose, and just had to be re-connected. I'm sure that doing all this voids some warranty or other, so don't do it unless this is a last resort and you're about to throw the thing in the bin. :-)