Currently the problem that you are experiencing seems to be an operating system corruption. Windows* 7 uses generic USB drivers to operate and in your case as you have an OEM system, the operating system could be customized for your configuration.
Currently I suggest to reinstall the operating system using the recovery disk or partition that your system manufacturer provided.
Thanks for the reply Victor_Intel. I used the Dell OS re-installation DVD and and installed the appropriate drivers for this specific system from the Dell website. The Intel identification and update utility reports that the chipset drivers are up to date, digging a bit further seems to indicate that the chipset driver installation file from Intel is the same as that obtained from Dell.
Hello again Andyc.
In that case, it seems like you have a hardware problem and should contact your system manufacturer.