The AGP expansion slot was designed to provide high speed transfers between a video card and the motherboard.
An AGP slot is actually a modified version of a 66MHz 32 bit PCI slot.
It was working before the update but now its not being listed in the device manager, instead all that is in Display Adapters is Microsoft Basic Video something.
AGP slots are especially susceptible to flakiness caused by old chipset drivers.
Even if you don't have an AGP motherboard, it's a good idea to be sure that your chipset drivers are updated to the latest version.
It is fairly common for computers to be running with old chipset drivers or to use the basic default drivers built into Windows.
If you're having any kind of stability problems with your motherboard then it's a good idea to install the latest chipset drivers.