USB Driver Dimension 4550

I recently re-formated my hard drive. In the past I mistakenly did a complete re-format of my hard drive so now each time I do, I'm faced with re-installing and setting up manually.

Problem now is, when I plug my flash drive in it says something like "High speed device connected to non-high speed  USB. In fact one of my flash drives doesn't even induce the U3 exec. file any more. nothing happens. I'm assuming I need to install the driver for the USB's, but can't find it on the Dell Disk. What is the name of the driver and can I download it?

Andy