Do you connect to the internet via USB modem ?
Is your printer USB printer?
I'm wondering if it is power related, I know some of the old Alcatel 'frog' ADSL modems could have issues with USB power as they didn't have their own power supply. I had problems with one that started happening after a period of time.
You could try a powered USB hub to plug the printer or modem (or perhaps both) into.