It would be worth going back to the original driver to establish that this is the change that causes the problem.
Standby and hibernation require drivers to meet a certain requirement in order to work. If the driver doesn't respond how the standby or hibernation function expect then these sort of problem occur.
It's not unheard of for a new driver to give x% performance increase but cause problems elsewhere.
Given your description it sounds as though the driver for the video card isn't allowing it to wake up whereas the rest of the system is trying to.