This happens to me all the time when I switch any hardware. i know it sounds stupid but your problem is probably just that your IDE cable isnt seated completely OR because floppy drives are so darn ghetto you may have to jiggle it around a little and actually hold your finger on the floppy disk after inserting it. These floppy drives are so rinkydink these days that sometimes you have to just persuade it to read the disk by physically munipulating it. You may even have to take the front cover of your case off so you can manhandle it to get it to read the disk. So...first try reseating your cable, if that doesnt work, stick the disk in and hold it down with your finger while the comp reads it. If that doesn't work, move it around with your hand to munipulate the inside of the drive..(really). If all else fails, go buy another one for $10, but I am sure if you just physically persuade it to read it will comply.