From Mexico.purplecow.org

USB Charging old Motorolas

For some stupid reason, Motorola on some of their phones like the L9 and some RAZR models broke normal USB charging from a PC (or other "smart" device).

The symptoms? Charges on a dumb USB wall wart, but fails on your laptop/sunray/other device.

The proper fix is apparently to install some crappy windows-only drivers from Motorola and/or hope for the best.

The quick-fix is to get a spare (sacrificial) USB lead and slice the data line to make it look like a dumb charger. Strip the insulation, cut a data line (usually white!) and plug it in. Windows might bitch about a faulty USB device, but current flows and phone charges.

Have fun, and be careful chopping up those cables.