Help! Cant get CD drives to refresh

Actually 2 related questions:

1. I have a new install (new Dell PC)of XP SP2 and when I change CD’s in either of 2 internal drives, Explorer does not refresh with contents of new CD or DVD.

2. When I insert a USB thumb drive, I hear windows recognize it’s insertion with a “ding”, but it will not show up in Explorer at all. It works fine on my older XP SP2 pc. Also a USB 12 in 1 reader works fine on older XP SP2 pc, but shows only 5 of 6 drive letters on same new XP SP2 pc. Is there a registry setting that may have been changed to cause these issues? The only way now that I can refresh CD contents, is to list contents of empty CD drive, then load new CD into drive and list again, this time with correct info. It’s as if cache isnt being cleared out.

Thanks for any suggestions!
Dave