Is it harmful to unplug a USB device while the computer is running, or to plug one in while computer is running?I guess it depends on the situation,

from my personal experience with these computers is.. if it is a USB device is not tansmitting data back and forth.

Example: printers, scanner.

If you unplug or plug these devices when the computer is on.. all it will do is day NEW device and just reload the driver detail.

However if you are scanning and printing and unplug and keep plugging the devices while they are doing something that might hurt the USB port and the device, because you keep interrupting it.

The most CONSTANT thing that you will notice are Flash/Jump drives. If you keep unplugging and replugging while transfering data it can damage the flash drive.
"Device is not formatted. Do you wish to format now."

When you stop a device you are just telling the computer you are done with it and turn it off.

I have pulled the device without stopping it first...*on a windows 98 PC and I have had no problems with the device as long as I exit all the applications that is using that device and making sure nothing is still running or using it.You don't mention your OS but I'll assume XP probably.

Windows normally ''likes'' you to use "safely remove'' options.  Just for removal - plug in is no prob as it either ID's the device if new or just takes it on board if familar.

As has been mentioned - do not try and remove when a peripheral is in use - PRINTER, flash drive, whatever.  Thing is - if you play safe and use ''safely remove'' it'll say ''no'' if it sees it in use.  That said - now and again it'll say that when it shouldn't!

Thing is - sometimes - a simple removal can leave a drive letter assigned to nothing ... which could be a nuisance.  Mostly tho - flash drives anyways I find - you can remove simply and not have problems to follow.the USB standard is defined as "hot pluggable"- obviously you don't want to mess around with it while it's transferring data and is in use, but physical damage is highly improbable, unlike almost every other connector- where it's unlikely. (VGA, serial ports, parallel ports, etc..)

THANKS for all the QUICK responses, all answers make sense.  More information on why I asked the question. The device I am talking about is "Majicjack" (VOIP) I and my wife use it only for long distance calls, I don't see keeping it plugged all the time if we are not using it for calls. The problem is it won't let me put my computer on hibernate while I am away.
Or there any ways around this??
Thanks all!

Chief95If your not using it, it should be plenty safe to unplug it when not in use.Thanks BC, so it won't hurt anything on my computer if I unplug or plug it in while my computer is running? 
I just want to make sure I UNDERSTAND your answer.

Thank you  sir.

Chief95Use the Safely Remove Hardware tool...that's what it's there for.