Windows 7: Network Computers unable to print unless Main Computer is on

Hello,

I reorganized my networking apparatuses about a year ago and I ran into this very strange problem just last week:

my network printer (Dell 3100cn) connected via ethernet to my router (with its own IP as well) is unable to process and complete jobs from the PC's connected wirelessly if the wired computer is not on.

This is immensely strange to me, because this problem came about very recently while I have had this setup working fine with no printing difficulties prior. I have tried reorganizing the the order of the ethernet cords on the router (i.e. putting the printer in the '1' slot and the computer in the '2' slot, etc...) but the wireless computers still cannot have their print jobs completed unless the main (wired) computer is awake.

BTW All computers are running Win 7 HP, and they have all previously been able to print without needing the main computer on.

Any advice is greatly appreciated. Thanks,
Frank