afaik, there are various programs that can disable standby since they need to be running all the time and standby would prevent them from functioning correctly.
As far as updating goes, make sure you update your windows, none of the drivers directly affect the standby mode unless one of your hardware components has developed a fault and cannot go into standby, in which case updating the drivers won't help.
So how can I find out these programs that disable standby? Is there a tool for it? What about if it is a hardware issue? How can I tell whether it is a hardware fault or something to do with programs?