I still have had no problems with restore points since I ensured that they were on the C drive and that there is enough space for them.

This is despite rumours that Diskeeper 2010 may be causing restore points to disappear. I run Diskeeper 2010 and occasionally Auslogics defrag too, and neither seems to be affecting anything adversely.

The most annoying aspect of this whole business is that Windows reports that it is creating restore points but isn’t telling you that they will be totally useless when it comes time to call upon one of them.