Office apps go mad when using managed com add-in

Hello all,

I created a (simple) com add-in using Visual Studio that I use in Word, Powerpoint & Excel. At start-up, the add-in adds 2 menu items to the file-menu. When the items are clicked, an instance of an (unmanged) com object is created an a method is called on that object.

Since the add-in is used, we've been experiencing some strange problems in the Office applications. All this issues go away when the add-in is turned of.

We had this issues on PC-A, logged on with USER-A, and not on PC-B, logged on with USER-B. Now ever since we logged on with USER-A on PC-B, that pc is having the same issues (for all users that log on to is).

1. When openig a word document with a lot of pictures (e.g screenshot), the pictures load slow. Sometimes, they don't show at all. When the user toggles the paragraph marks, the pictures appear.

2. In powerpoint (in some documents), pictures are not shown on the slides. The are visible in the thumbnails though. When the picture is selected, you can see the 'picture frame' and you can change the picture's properties. It's like the picture is transparent.

3. When opening a Word document with some old Cliparts (from the Office 97 clipart library), Word starts using a lot of CPU and just hangs when the user start scrolling the document (this is NOT the case when you log on to the pc using a remote desktop connection!!!).

I don't expect to get an answer here that will solve the issues, but I'm looking for some information on how to figure out what exactly is causing these issues.

Thanks for you time,

Sven