I bought snow leopard and it won't install

Question

I bought Snow Leopard and it won't install.  It keeps saying, "You can't use this version of the application Install with this version of Mac OS X.  You have Install Mac OS X 23.1.1."

Answer 1

Hi stedman, in theory, since the machine is a 2008, going from Lion to Snow Leopard should be possible, but requires the usual startup proceedure, boot holding the C key, then since ML is on the hard drive you must do an erase and install.  You cannot do a reinstall.  I say in theory because if all firmware updates have also been done following installation of Lion, there may be a firmware block now causing problems reading the SL disk.
That is the problem we all face trying to help diagnose these situations remotely...incomplete information.
So, for bistraung: how exactly are you trying to install SL?  Are you trying to restart your computer with the SL disk in the optical drive and holding the C key?  Or, are you trying to read the disk directly?  You cannot do the latter.
Do you have a backup of the drive?  If you do the SL install, you must erase the hard drive before installing SL which means you lose everything on the hard drive.  So me sure you have a backup or you cannot get anything back.
Best approach would be get an external hard drive, format it Mac OS Extended (Journaled), GUID partition table, and then use Carbon Copy Cloner to make a bootable clone of the internal hard drive.  I say CCC instead of SupperDuper since CCC does a better job of also cloning the Recovery Hard Drive, which will be important if you need to work on Lion at all.
With a bootable clone, you can boot to either SL on the internal drive or Lion on the external drive...gives you options.