In my case, i am using a Realtek onboard sound chip and aside from my speakers i do just have one more sound device installed which is my headset.
Whenever i do a driver update, the installer first uninstalls the old driver, reboots, installs the new one and reboots again. So far, so usual. However, each time FxSound is missing its active sound device due to unavailability from the driver update, it crashes. Could help to catch this situatin a bit more nicely; for example switching to another available sound device when the used one is lost (my headset in this example which is not affected from the update).
The other thing happens after the driver is updated. FxSound does not remember the last used device, is not switching to another available device or at least giving out an error. Its just dead until i do switch sound devices at least once. Being that not a real issue, it could really confuse lesse technical experienced people since they would end up with no sound output at all in such a case. I am quite sure, FxSound cannot find the last used device due to the driver update but in the end, the device is exactly the same with the same name and IDs and what not.
Maybe that helps.