UnseenMenace
Thanks for the reply. I did recently install some updated SIS chipset drivers, although I have no Adobe programs installed on it. It is a fresh install with all Windows updates and only NVidia PureVideo and DivX installed, neither of which check for updates as far as I am aware.
Automatic Windows updates are turned off as well. The LAN is via a USB wireless dongle, however I shall disable that tonight and see if it makes a difference. I have just set the Windows clock to 11:55pm and put it in S3 standby, but it hasn't turned itself on at midnight which is when I thought it might be happening!
I have enabled bootlog, but it doesn't seem to log the time of standby/resumes so I can't pinpoint exactly when it is happening.