when i turn my ps2 on i get a weird sort of humming noise,then it takes a while for the disc tray to open i put a game in. somtimes it runs and freezes making the same noise it sort of sounds like the disc just stops any suggestions?

your lens needs to be either cleaned or replaced its having ahard time reading the disk

Remove the Power and AV Plugs, open the system up PAYING VERY CLOSE ATTENTION TO THE POWER/EJECT RIBBON) once off remove the retaining screw for the buttons pull the buttons off and tape them to the side of the PS2 Temporarly to prevent damage open up the upper cd tray cover its held down bt 4 Very Small Philis Screws (an Eyeglass Philips screwdriver will be needed) and clean off the lense if you can go by The Source ( Radio Shack) and pickup Lens Cleaner, Do not use Isoproprial Rubbing Alcohol it will remove the fine coating off the surface of the lens, and lightly swab the lens not applying to much pressure..
pop the CD tray cover back on plug it in and try a Disk.. you do not have to screw the cover down as of yet but make sure it stays in place.. and be carful not to touch any exposed boards or components, Damage may result to the playstation2 itself or yourself..

if that doesn;t help at all pull the cover off again make sure the tray is open before doing this, you will find a white spindle at the back of the tray in the center turn it 2 clicks counter clockwise to lift the lense a little higher.. if that doesn;t help try clicks the other direction.. do not advance more then 3-4 clicks you may damage any disks you insert because the lens was raides to far up

if that doesn;t help you may need a replacement lens to repair the unit :)

Hopefully you can get your system back up and running :)