Sharp MD-MT99, cannot read disc

[Tangur]

I've kept my minidisc player on a desk for 2-3 months (it was not directly exposed to light, it was always kept at room temp). Anyways, I needed to use it again, so I just push play, it starts reading the first track, goes on to the second one, then at the 3rd it says 'cannot read disc" and it shuts down, i tried with different disc, but always got the same result. i even got my discs checked by some friends and they could read all the tracks. i tried removing the write-protection from the disc so i could erase it but once i push play, it gives me once again "cannot read disc". i was thinking that the laser head might be damaged.

thanks