I am using Borland's Reflex, an old dos program. It uses graphics, even for text. It runs on only two of my five computers with xp os but not on the one that just got a new motherboard and video card (although it did run on this computer until last week when the hardware was changed). What makes the program run on some computers and not others? How can I make the program work on the other computers?

Check out the link below. "Restoring the missing files" 16-bit MS-DOS Subsystem error while installing or running a DOS application. http://windowsxp.mvps.org/16bit.htm Tufenuf

Thanks for your response. I copied the 4 files (command.com, command.exe, config.nt and autoexec.nt) from the computer running xp that will run Reflex onto the computer that used to run it but does not since some hardware was changed. Reflex won't run and I get the same error message. I am wondering what is DIFFERENT about the computer that will run my dos application. Both HD's are NTFS and os is xp professional. I also tried changing the parameters of reflex (like windows compatibility) without success. I wish I knew what xp does step-by-step to make it run in the one computer where it does work and I would check the steps in the other computers.

It is quite likely the graphics resolution, the NTVDM (sudo MS-DOS) is based loosely on MS-DOS 5 which is nigh on 20 years old, also it could be IRQ/Memory Mapping conflict.. Personally would advise you to use a Virtual Environment like MS Virtual PC: http://www.microsoft.com/downloads/... http://en.wikipedia.org/wiki/Micros...