Do you mean that when you put CD inside,the EXE file starts by itself such as a game installation Window?
And now when you installed SP3 it doesn't work anymore?
Because usually "autorun.inf" files are used for that,but they can be used for many other things too lol.Here is an example of "autorun.inf" contents which start a specific EXE file when CD is inserted:
open=File.exe
label=TEST
icon=Icon.ico
By the way autorun files can also do the SAME from the USB storage devices too,only the autorun code is a little bit more complex,but it's possible.I have done it dozens of times.
Of course depending on what you want,in some extreme situations you might also need to create your own VBS and BAT files.I have done it dozens of times.