Disc stopped working but not a mark on it?

[Paperghost]

My space channel 5 part 2 disc suddenly stopped working. I bought it unopened - only used it twice, when i got it for about ten minutes and last night for an hour or so. was working fine via DCX boot disc last night.

this morning, put the game in as normal after the DCX "press start to continue after swopping disc" message.

the dreamcast logo comes up, then SEGA, then the screen just goes black and nothing happens.

there isn't a mark on the disc. ideas? i posted this at another DC forum, and someone suggested it was the dreamcast itself starting to die off, rather than the game (which is in absolute mint condition).

i tried another import and that loaded, and the few PAL titles i've just tried worked too.

/ edit - don't know if this is useful or not, but the disc keeps spinning until you open the lid - doesn't stop when the screen goes black.