You might try a different USB port, if available. Some ports are "current-limited" and don't put out enough juice for charging. Finding one on your computer is pretty much hit-or-miss, because most computer manufacturers don't disclose which is what in their documentation.

I have had good results with an aftermarket charge/data cable on my RAZR V3 by plugging it into a Compaq laptop and leaving the computer plugged in and in Standby mode (I just close the cover, which blanks the screen). It's a great feature when traveling, because it eliminates the bulk and weight of Yet Another Charger.

It could a factor of the USB spec and Mot laziness. USB, by default, delivers up to 100mA at 5V (500mW) to a device. If the device asks for more, up to 500mA (2.5W), the PC may deliver it. A normal USB hub can deliver a total of 500mA for all connected devices. Most computers should have more than one USB hub.

The device has to be powered to ask for more than 100mA. If a device tries to use too much power without asking, the PC can tell it to shut off. Any idiot circuit designer should be able to power the USB logic using the 100mA default power allocation (I've done it). Perhaps the RAZR's chipset is such that the chip that does the USB communications requires more than 100mA so that it cannot initially ask for more power, thus not working at all. (Just a guess).

If you go to System in the Control Panel and under the Hardware tab click on "Device Manager", you can see a list of USB hubs ("Universal Serial Bus Controllers").

For each hub listed you can see the power use. Right click on the Hub, then click Properties. Go to the Power tab and you can see a list of devices and the power they've been allocated, as well as the maximum that can be allocated.

Note that you'll see more hubs than you can find on the outside of your PC. My notebook has two USB ports, both on the same hub, but it has 5 listed USB hubs (internal devices, etc.).

This is for XP. Win 2000 is similar. Dunno about Vista.

I'm sitting at EWR waiting for a flight and decided to try hooking up my old V3c that would not charge from any other computer. But it is working with my new ASUS eeePC

I wasn't going to get into that, because nowhere in the Properties sheet is there any indication whether a specific hub feeds the left-side port, or the one on the back, or whatever. Looking up the current-carrying allocations is an interesting diversion, but of no real practical value that I know of.

On a semi-related note:

Has anyone ever had success charging a SLVR or RAZR with a non-motorola wall charger?

I have 2 different mini USB chargers (for headsets and such) but they are not motorola and my SLVR will not charge off of them, I lost my wall charger so the more alternate ways the better.

Do I have to remove or connect some pins in the mini USB cable, I don't quite get why another USB wall charger doesn't appear to work.