Hello, after i lost my Mac Pro's original System Install DVD, I started a "battle against nature elements" trying to find a new OS X install DVD to replace the one I lost. I have a Mac Pro (mid 2010), 2x2.4 GHz Quad Core Xeon which came with Snow Leopard Install DVD (OS X 10.6.4) as it is shown on this Apple Support link https://support.apple.com/en-us/HT204319. I made further updates through the Software Update utility till reach the lastest existing version of Snow Leopard (10.6.8). I felt like blessed days ago when i found out that Apple still sells a physical Snow Leopard install DVD ( Retail )http://www.apple.com/es/shop/product/MC573E/A/mac-os-x-106-snow-leopard which means it can be installed on any computer ,unlike the original DVD shipped with the computer which only works with that specific machine. So I purchased it and just received it yesterday. Decided to give it a try and to make a clean install on one of my SATA internal Hard Drives. My joy didn't take long to turn into disappointment when i realized the dvd wasn't working as expected,it stopped the install procedure before completed leaving the destination HD with a bunch of APK files impossible to execute,and even worse, there was no a way to boot the computer from the DVD (pressing C key) I only got a grey screen with the apple logo in the middle and nothing more happened. Trying to find out the cause of that behavior i checked out the dvd's case and i saw a tag glued on its front side which specifies what Snow Leopard version the DVD contains and this is 10.6.3. So this is the current scenarion : My Mac Pro was shipped with Snow Leopard 10.6.4 and as i think to understand reading the first link i postedhttps://support.apple.com/en-us/HT204319 , Apple says :"Avoid trying to use a version or build of OS X that's earlier than the one that came with your Mac." Now my questions: 1.-Could it be the 10.6.3 version (earlier than the one shipped with my mac) the reason why my Mac refuses to recognize the DVD? or being a retailed Snow Leopard dvd should it work on any machine no matter the version? 2.-If the question is Yes, how could i make it work if that is possible. (I suppose a work around could be to take out the SATA HD from the computer go to a friend who has an older than mine Mac Pro which accepts the 10.6.3 DVD and make the installation on his computer, but my wish is to be able to do it by my self ,at home ,on my Mac) Have read i could create a bootable thumbdrive of my current OS 10.6.8 any help or link about that option? Sorry the long post. thanks in advance.