Usb Problems

My root usb has stoped working for some reason i have tried removing the drivers and re-installing and still nothing. I also tried various diffrent types of usb devices with no luck. What should i do?
My secound query is i have a 2.0 NEC usb pci card installed. My problem is the not all devices work on it. For example if i try to link my printet up with it or my flash drive to it it wont work…but it does work for connecting my phone up and other device. Why?
Thank for you help