The USB (Universal Serial Bus) or better known as the (Unsupported Serial Bus) is being shipped in many machines today which are pre-installed with WinNT v4.0, but Windows NT v4.0 does not support this USB bus.
Because WinNT v4.0 doesn't support the USB, there is no way to control it (unless each manufacturer comes out with their own drivers) and thus numerous problems can and will occur with serial devices.
If you have a machine with a Serial mouse and a Serial modem, you'll experience problems. If you want to set up a RAS server on one of these USB installed machines, you'll have problems. If you have a serial modem and a serial joystick, you also experience these problems.
Windows NT v4.0 requires all hardware control to be made through the NT HAL (Hardware Abstraction Layer) as NT does not allow direct hardware control. Therefore each hardware that you wish to address, must be forwarded to the HAL and then the HAL will send the command out to the desired device.
The problem with the USB bus is that it is relatively new and therefore, Windows NT doesn't have a HAL module that supports this bus. The bus itself, being a serial device, does require an IRQ and an I/O address, but Windows NT isn't aware of this and thinks that the IRQ and I/O being used by the USB is free and available to assign to other devices.
Many people mistakenly think that if they disable the USB bus in BIOS, then there will be no problem, but think about that for a minute... The BIOS in which they are disabling the USB in is DOS BIOS and is completely ignored by WinNT. Therefore, even if you disable the USB in BIOS, it won't be disabled when NT is running and therefore will take up an IRQ and I/O address which NT is unaware of.
The only way to fix this problem is for Microsoft to come out with a standard USB supported Windows version (which Microsoft claims will be available in NT v5.0 and Win98), but as NT v5.0 is not out yet, that newly purchased USB bus installed machine with NT v4.0 pre-installed will give you all kinds of trouble.
There is another way to temporarily solve this problem, but that temporary solution is not up to the individual, but up to the manufacturer of the PC purchased. If the PC manufacturer will provide a HAL disable driver which can be set under Win NT v4.0, then you can turn the feature off under Windows NT v4.0 until v5.0 is made available.
That about sums this problem up...