Vista 64 Prem, HP Pavilian a1268c, error NETTDI64.sys happens as soon as I step away an about all I get to see before it reboots. Sometimes it happens in Micrsoftword, Explorer, Quickbooks and doesn't seem to be doing anything constant. I am unfamiliar of Vista 64 but had some networking experiences. I have upgraded to dual screens with a Nvidia 8500 512 memory. Otherwise it is stock system.