I have 3 mac68k with the same kind of problem. I sent messages to this
mail list before, but the problems remains the same.

It look likes a simple problem, but I didn't installed NetBSD yet just
because this problem.

I have original disks of System 7.0.1, but when I insert "Disk Tools" or
"Install 1" disk, the face ":-)" appears, but the disk ejects a few
seconds later.  This problem happens in all the 3 mac68k (2 LC II and 1
SE/30). When I insert the "Install 2" or another disk with no boot, the
face ":-)" don't appear, and it ejects a few seconds later too. In the
last case, I think it's normal, but in the first case, I don't know what's
the problem.

Anybody with the same problem? I have no idea what's going on.

Thanks.