Ok .. lets use a simple example ... Imagine you have Counter-strike installed on windows server or XP, the key is stored in the registry in Windows. After you dual boot to longhorn, if you install or run counter-strike it will work on xp and the key will be stored in longhorn's registry. After this if you switch back to Windows Server or xp, if you try to run counter-strike you will see that the registry information for it wil be reset somehow, thus making you install counter-strike in Windows Server or Xp. also ... if you boot back to longhorn the same thing will happen and you will have to add the registry keys again or re-install. This happens also to ACDSEE, and other programs ... Hope I made clearer ... Greetz Bomn