Hi All, I know the details are sketchy, but it's all i've got at the moment. A friend of mine has sent me an email about her laptop. Laptop Make and Model Unknown O/S Unknown When she plugs any USB devices into her laptop when it is running of Battery, it runs fine. When she plugs the USB Devices into the laptop with it connected to the mains, the screen freezes. Any ideas.

Whats this, some kind of test. Solve a problem with the minimal amount of information. With the information provided the first indication would be that the USB device might be drawing to much current. 500 mA is the max. What type of USB devices is she using? Stuart

Hi Stuart, I know is a crazy post, i'm in the IT industry but that's all the information i have at the moment. I have emailed her and we have done some testing, i have got her to disconnect all devices and just connect her Alcatel Broadband modem. Still the same. I don't think this is a power issue as on a power issue, the USB device does not work. The PC stays working. Any more ideas. Phyto

Well the Alcatel USB Modem does need 500mA. So anything else plugged into the same port could cause a problem. There is always the possibility the USB port is not supplying the 500mA it is supposed to do. However, I would expect the opposite to what you have i.e. fine on mains, not working on battery. It has to be something to do with the power supply. Could be a fault has developed in the battery itself and the battery is drawing to much current from the mains. Have you tried running from the mains with the battery removed? Stuart

Good idea, can't think why i didn't think of it. But you're right, iexpected the opposite to what happens if it was a power issue. I'll get her to try that and let you know. Thanks Phyto