When run on hardware for which 32-bit drivers are not available, Windows 95 may be forced to use MS-DOS and/or the BIOS for access to the paging device. When paging through MS-DOS, the VMM changes its behavior in significant ways, and new rules apply to existing VxDs. Windows 95 will also page through MS-DOS if the system is running in safe mode.
Make sure to test your VxD on a configuration that pages through MS-DOS. One way to accomplish this is to go to the Control Panel, and select System, Performance, File System, Troubleshooting, then 'Disable all 32-bit protect-mode disk drivers'.
Special circumstances that apply to paging through MS-DOS will be noted as they arise.