Why doesnt my xbox like to read the disks?

alright well i have the xbox pro model the white one with the 60 gb Hd and its been doing this for a long time and really now i just wish it would stop you know i have put up with it for a long time but what happens is when i put a disk in it just comes up to open tray like there is no disk in, so after opening and closing the tray about 50 times it will eventually read the disk, a trick i found that used to work was to take the disk out and close the tray with no game then insert a game disk nest time you opened it, but now even this doesnt work so please if you have the same problem or a way to fix it i would appreciate it