Because since Vista all the drivers on the your PC had to have Microsoft Driver Signing a lot of old programs like virtual CD/DVD drives don’t work anymore. This signing costs about 500$/year for any software that adds drivers to the system. Some older software created virtual devices in order to work and can not be used in Vista or 7 because of it.
There is a way how to disable driver signing. We need to start Windows in Test Mode so that it will not check every driver. The drivers you install and use in Test Mode will only work there, after you disable Test Mode again they will no longer work even if you managed to install them.
To activate Test Mode you need to start a command prompt with administrator rights. Click start, write cmd, right click on cmd.exe and select “Run as administrator”.
Inside the command promt write the following:
bcdedit.exe -set loadoptions DDISABLE_INTEGRITY_CHECKS bcdedit.exe -set TESTSIGNING OFF
Now you need to restart Windows and after it starts you will see written just above the clock and date Test Mode. Now you can install any driver you like.
To deactivate Test Mode just start another command prompt with administrator rights and write:
bcdedit.exe -set TESTSIGNING ON