Q: MacBook late 2006 c2d can not install leopard

You must first erase the drive and do a clean install or you must use Archive and Install option.

Make sure your Leopard disc looks like

or if you have Snow Leopard, that it looks like:

Note, your machine is compatible with up to 10.7.5, but first you must make sure all your applications are post 2006, and do not need Rosetta.  See my tip on upgrading to 10.6 and beyond.  You can update to 10.6 directly from 10.4.x without going through 10.5, but you still must buy the 10.6 retail.    And then you can update to 10.7 directly only from 10.6.6 or later.

That is a grey, Machine Specific disc and failure to install it may indicate that it isn't the disc your MacBook was shipped with.    You will therefore need to buy a new retail disc.

Seventy one is correct.  If your machine was releaased new in 2006, it came with some version of Tiger originally.  Only Leopard retail, the black discs I mentioned earlier will work if you need 10.5 for some reason over 10.6.  If you have support for 10.6, it is cheaper and still available from the Apple Store, and getting the white disc I mentioned.  So look at your software compatibility against the links I gave and see if you  can go to at least 10.6.