in one win98SE machine, i can't use any usb flash disk, it just gives usual blue-screen Exception Error 0E xxxx:xxxxxx IOS (4) vxd stuff.
however, after checking bootlog.txt content i found suspicious entry:
[0015EE7A] Dynamic load failed C:\WINDOWS\system\IOSUBSYS\intelvsd.vxd : [0015EE7A] Not a valid device - possibly corrupt
after removing that file from IOSUBSYS directory (renaming it into antyhing_else.vxd, wont work)
, NUSB is now fully functional in that machine.
minimum API requirement checking can be done using wdmcheck under win9x system.