Hi, I have an old(er) mac mini - from 2007 with the c2d 2.0ghz CPU. I have just finished wiping clean the disk inside of it, rewriting with zeros, etc. - it now has a completely blank, perfectly functional hard drive in it. I power it up, insert the retail $29 snow leopard disc I bought from Amazon, and ... It just sits there rebooting itself over and over again ... gray apple comes up, spinny icon thing spins .. then screen goes black and it repeats that. Has done it about 12 times now. What am I doing wrong here ?