Hiya, I am here with a strange problem. It took me so long to identify the problem with .NET Framework 2.0. Firstly i have developed a VB.NET based Addin for Excel and it is working fine on my machine and all the other machines. Previously it was not working on test machines or any other machines or it works sometime and sometimes it's not. I identified the problem of this uncertainity was .NET Framework 2.0 because it only works with Windows XP with Service Pack 2.0 or higher. The annoying thing was it works sometimes and sometimes it doesn't. Anyways now i have gone through all of that bad time and figured out this in the last, Microsoft XP should have service pack 2 or higher for .NET framework to work properly. Now i have given the demo CD for one of my client and they installed that software on 2-3 machines and the Addin comes up on the Excel Sheet on the toolBar, but it seems like it is not working at all, i mean all the option on that Menu are not working. And i am not certain this time what makes it wrong, i have a fresh PC with office 2003 on of my test machine with Windows XP SP2 and framework 2.0 and it works fine. All machines on my client side has Windows XP with SP 2 and .NET Framework 2.0 installed. I wanted to figure this out, hhow can be it possible to find out what is missing on there machine which doesnt let my software work. Please i am desperate to know the answer or any thing which can lead me further to resolve this. NOTE : I have installed KB908002 (Shared Add-In Support) and set them as pre-requisite with my installer (as i told you its working fine on all the machines in my office) Thanks, Asim.