I'm having a problem running two computer programs on my computer. They have always worked before and just recently when I click on the program in the start menu I get an error message as follows. (16 bit Windows subsystem) C:\WINDOWS\SYSTEM32\AUTOEXEC.NT. The system file is not suitable for running MS-DOS and Microsoft windows applications. Choose 'Close' to terminate the application. My question is what caused my computer to not run these programs any more and how can I fix this problem?