OK..It was originally a MESH built system and the two original (Promise) HD's are still operational. The key Disk is C: which I store nothing on other than of course Program files along with the XP operating system. I (PC World) added a third Disk G: ( Seagate 500GB) 18 mths ago. It is this Disk, (50% free space) that is now playing up.. I can access files, play MPEGs, MP3's fine from the disk BUT any interogation of it, Virus checker, Defrag, moving files remains VERY slow.....Please let me know what other info you need. Thanks CZ