Hello Mike and welcome to the forum.
Here you may receive several replies that will give you various options,take heed and try the options posted.
Ok,i have this feeling it could be a Microsoft update issue.
Firstly you could try system restore taking the system back to before the problem arose.
Im limited to what advice to give at the moment as im on an xp machine and not at the Vista.
You maybe able to try a repair by tapping F11 or F10 normally on startup,this should bring up three options.
1) Restore to factory settings (destructive) all data will be lost.
2) Repair windows saving data.
3) Repair windows without saving data.
Maybe listed slightly different.
Or refresh all usb ports:
Enter Device Manager and uninstall everything under usb headings and reboot,Vista will reinstall the Generic drivers for the machine.
It certainly sounds like a driver issue over hardware.
Does device manager show any yellow exclaimation marks ?