Read http://support.microsoft.com/kb/314464 and you find the answer is to install the driver for it.
There is no issue for speed, performance if you don't fix it. This can be cosmetic and as such I'll just leave it as-is, where-is and use the machine without fixing.
Using Windows XP Pro SP3. How do I get rid of an "Unknown Device" with a Yellow question mark in my Device Manager? By process of elimination, I believe it to be my UPS by American Power Systems. Attaching it to the computer was an optional step and it does not need to be there to function, and in addition I am unable to find the software to reinstall it.
I have tried deleting the device in the device manager but it always returns, and I get the old "Windows XP has found new Hardware do you wish to etc. etc."
Thanks in advance for any help offered,