restoring from time machine in snow leopard

I recently sold an iMac on ebay. It was an iMac 10,1 with OSX 10.8.4 I purchased the Snow leopard discs from apple and rebooted the computer using those...

The buyer recently sent me a message on ebay saying this:

"I have been trying to restore my backup via Time Machine, and the instructions tell me when the Installer disc opens to click on Utilities, then choose Restore System from Backup. But when I click on Utilities, it asks me to Restart, everytime. Do you know if I am doing something wrong?"

Can someone hepl me/him?