If you’re running Leopard or Snow Leopard on a “hackintosh” netbook, don’t allow it to upgrade to Snow Leopard 10.6.1, or Leopard 10.5.9. The core kernels in those update kill off support for Atom-based netbook CPUs, which is almost certainly the processor inside your netbook.
There are likely fixes in the works by the hackintosh community, and you might be able to retain your current kernel and upgrade, if that’s something you know how to do. Still, for the time being, it seems like sticking with what you’ve got is a pretty wise move.
OS X Daily via Gizmodo