There seems to be some confusion going on here. ASIO is not a driver it is a protocol, and an ASIO compatible driver therefor is usually supplied by the audio interface manufacturer as mentioned above/before. This is usually only with the more expensive audio interfaces.
Realtek has no ASIO driver, it is a basic embedded soundchip on most mainstream motherboards. You can use the driver for it that is supplied by their site, i think it was a Taiwanese site. That driver is i think either DirectX or Windows WDM compatible.
The “Generic Low Latency ASIO driver” driver is some sort of virtual driver that gets installed when installing certain Steinberg Software. At least this is the info i found with a small google search.
You could try as suggested above to install ASIO4ALL as a wrapper for your Realtek audiocard. Although this is not a real native ASIO driver, it might solve your problem.
Rack, can crash if an input/output that you are trying to assign to it is “in use/occupied/reserved” by some other software or system setting on your computer.
Hope this helps.