1. Using Regedit find the key below, creating it if it doesn't already exist.
2. Create a new DWORD value, and name it 'NoRealMode'.
3. To disable the real mode DOS modify the value of 'NoRealMode' to '1', and to re-enable it again later change the value to '0'.
Note: You need to reboot for this restriction to come into force.
Key:[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\WinOldApp]
Value Name: NoRealMode
Data Type: REG_DWORD
Data:(0 = disable, 1 = enable)
