The main factor is that the OS works fine to begin with. There is no reason that overclocking should cause problems for the OS directly - it would be because some component. ie mobo, cpu, memory, etc begins to fail because of the overclock. So in theory, if you then upgrade that component to be able to handle the oc, then any problem should go away. Of course you could also lower the overclock to fix things, but I'm sure that suggestion will fall flat in this forum.
What problems are you speaking of?