Q: I have a Mac SE. It gives the happy mac icon then ejects the boot disk and gives the ? disk. Whats wrong with it?

The boot disk may be bad/damaged. If possible, try another one. You may also want to test starting with the four keys Command(Apple) + Option(Alt) + Shift + Delete(Backspace) depressed. Also, any change after a PRAM reset?

http://support.apple.com/kb/HT1379

Jan

It's also possible that the disk drive needs cleaning.  But the most likely scenario is your boot disk is bad.  You can get new ones here:

http://www.rescuemyclassicmac.com/

Is it a plain Macintosh SE (and does it have an internal hard disk)? Or is it possibly a Macintosh SE FDHD? The former model is for 800K floppies; the latter can use 1.44 MB disks as well.

Do you have access to another pre-1998 Macintosh computer (with a built-in floppy drive)? If so, there are disk images that you can download from Apple, and then use Disk Copy 4.2 to create bootable disks. If necessary, but only if the SE is of the FDHD variant, you could even use a Windows PC (or possibly a Mac OS X computer with a USB floppy drive) to create a boot floppy. Please post back should further information be needed.

Jan