After installing printer, USB port not providing power

I hope you can help a tech illiterate (OK semi-illiterate).
I hope this is the appropriate section.
A few months back I installed a HP laser jet all in one printer onto my old Dell Dimension 4550. I tried unsuccessfully to get it to work properly and to work on our home wireless network and finally hired a tech guy to do it. He wired it into our wireless router via (I forget the term- the wire that looks like a larg phone jack wire) which has it working fine. The trouble is the front USB port seems towork only intermittently to power my external hard drive. It's a case that holds a laptop harddrive and takes its power from the USB port. It also doesn't work for my daughter's iPod. It will connect for my digital camera and Palm Pilot both of which, I beleive only connect, but don't draw power. Around the same time I also installed a second hard drive.
I can sometimes get the external harddrive to power if I do some combination of restarting/turning off and on the printer, but not consistently.
Any thoughts?
Am I overtaxing my power source? Is it a hardware problem? Is it (as Dell chat suggested) a printer driver problem?

Any thoughts/suggestions will be greatly appreciated.

Oops-it seems to be a peripheral issue rather than a USB port problem. The conector came loose on the hard drive enclosure and I can get my daughter's iPod to charge from the port.
Sorry not to check the easy first.