Managed addins/components that sink events on the Application object may cause problems with OLE functionality in that instance of Excel, resulting in errors or possible crash of host application trying to edit Excel embedded objects.  Managed addins can avoid this problem with custom code. Users seeing this problem can avoid the problems using an Excel instance that does not load the managed addin.

For details about this problem and what developers building managed addins can do to avoid it, see this post:
Excel OLE Embedding Errors if you have Managed Add-In Sinking Application Events in Excel