Hi, Bruce~
Sounds like you have a problems with the IDE subsystem.
The thing you need to know about the system is the type of chipset on the mainboard. The ways to locate this vary, but with a Dell system, you can look up the specifications for the system by entering the service tag number or the system model number on this <A HREF="http://support.dell.com/us/en/register.asp?redirect=yes&segId=5DS" target="_new">page</A>. If that isn't a viable option, you could call Dell, give them the model number, and have them identify the chipset. Or you could open the case, and look at the chipset on the mainboard.
The chipset is likely to be the Intel 440BX PIIX4e, if the system is in the OptiPlex series, but I can't be sure without extra information.
With this information in hand, you can download and install the chipset drivers, which will almost certainly take care of the problem, without resorting to Registry editing. Drivers for supported chipsets can be downloaded from <A HREF="http://support.intel.com/support/chipsets/driver.htm" target="_new">here</A>.
That's my opinion.
Toejam31
<font color=red>My Rig:</font color=red> <A HREF="http://www.anandtech.com/mysystemrig.html?rigid=6847" target="_new"><font color=green>Toejam31's Tantalizing Tantric Toy</font color=green></A>
<font color=red>Second Rig:</font color=red> <A HREF="http://www.anandtech.com/mysystemrig.html?rigid=15942" target="_new"><font color=green>Toey's Dynamite DDR Duron</font color=green></A>
____________________________________________________________
<font color=purple>"Procrastination on your part does not constitute an emergency on my part."</font color=purple>