I used a 260W up until a couple of months ago. I had this same problem, but only occassionally. In my case, the short term fix the first few times it happened was to let the battery drain entirely, then re-charging completely before turning the unit on. The long term fix turned out to be a software update, which took care of the problem completely.
If you have not done this already, there will be some software that you will automatically be prompted to install on your computer so that it can communicate with your 260. Install the software and plug your 260 into an available USB port.
Once you have done this, your computer will recognize your device or prompt you to "search again" by clicking on a button. When your computer has recognized the device, click on the My Dashboard tab. You'll see a box "Software Updates" in the bottom left hand corner. If there are any updates available for your device, they will be listed.
Once installed, this should take care of your problem.