As I mentioned over the weekend, I've transitioned over to Office 2007 and am mostly pretty happy with it. I like the Outlook To-Do Bar more and more each day.

However, I ran into a problem yesterday that I couldn't find any resolution for online and I figured it'd be worth archiving here so the Google tubes can find it later.

Basically, I opened up VS.NET 2003 yesterday and got errors from two of my add-ins. These were CodeRush (the DXCore, to be specific) and the VSWindowManager PowerToy. Both of the error messages indicated that there was a FileNotFoundException being thrown while they tried to add items to the Visual Studio menus. Only the CodeRush exception told me which file was missing and it simply said 'Office'.

Now, I had used VS.NET 2003 last Friday (our desktop product is in 1.1 for now, but our newer web product is in 2.0) and it worked fine. The file name in the exception reminded me of pretty much the only thing that had changed on the machine since then -- the Office 2007 install.

I thought it was odd that VS.NET, which doesn't require Office to be installed, would be freaked out by an Office upgrade. In any case, I fired up the VS.NET 2003 installer and chose the Repair option. It's worth noting here that the Visual Studio 2003 installer is quite possibly the slowest-running install in the history of computing. Go get lunch while it runs... when you're back, grab a book, take a walk, or paint your house. Choosing the Repair option in the installer doesn't appear to be any faster than a first-time install.

Once that was done, I reinstalled CodeRush/Refactor and the VS Window Manager just to be safe... and all is well. Since then, I heard back from the DevExpress support folks (who rock) that they've seen this issue before. The problem occurs when the Office.dll and Extensibility.dll files are removed from the machine's Global Assembly Cache (GAC). Those files are needed by Visual Studio add-ins that want to hook into the IDE.

My best guess is that the uninstall of Office 2003 removes those files from the GAC (though they may still be around somewhere else on the machine) and they're not re-registered by the Office 2007 installer. The Office 2007 install does give you the option to uninstall 2003, or you can leave it there... and I did opt to have it uninstall.

Hopefully, anyone who suddenly finds that their VS.NET 2003 install isn't loading add-ins will Google for "Visual Studio 2003 add-ins loading exceptions Office" and come across this post at some point.