adminstrator has prohibited access

I own a xp computer and am the only user. I ran AVG Antivirus and removed all threats. I just want to access my usb/1394 mass storage and cd/dvd devices. The error messages are “adminstrator has prohibited access to usb/1394 mass storage devices” and “adminstrator has prohibited access to cd/dvd devices”. How do I rectify the problem? The devices appear greyed out beside a red circle with a diagonal line thru it.