Printer - Time Out/ Stop Working

I am running Windows 7 Professional 32 bit and I have a networked copier and a couple of local printers for my computer. I have recently set them up - have the correct drivers for these printers and they work - most of the time.

The problems that I am having is the printers will suddenly stop working. If I go into the Devices and Printer Control Panel they are still there but they are faded like they are off line, even when they are on and running. I have found that the only thing I can do is to restart the whole system to get them on-line again. This is happening at least once a day but with infrequent intervals - It happened in the first five minutes after I turned on my computers this morning. But after about 6 hours yesterday.

Any suggestions?

FOLLOW UP: So after talking to a couple of my IT people. I found out that my default printer was going to sleep and so it was messing up all my other printers and having them freeze and not be able to work even though they were ready to print. So I changed my printer default and that should help the problem. we will see what happens next...