When Usbsupp.exe is used to install usb support with Win95, it wont allow you to reinstall without first uninstalling the original.
For some reason it is not always possible to uninstall it, however
Wdmusb.exe will reinstall over itself.
This was very useful in getting an AMD K611 450 to run on a FIC 503+ motherboard with VIAMVP3 chipset.
If Wdmusb.exe is used under the same circumstances and an exception error occurs due to Ntkern.vxd, then the AMD K611 update needs to be installed again. If the system will not even start in safe mode then disable the internal cache in the BIOS setup.
Once in safe mode run the usb support
and AMD update and any IDE PCI patches
and reboot enabling the cache.