VB.net to replace unstable excel add-in
 

I keep getting excel link issues when people open excel files with an add-in.
The add-in has user-defined functions. From there I open the excel file in
VB.NET keeping the excel app invisible only using it for the logic produced
showing it in a nice windows application. However, data link issues occur for
no apparent reason, its hit and miss. I've tried just about everything to
prevent them. And I cannot use the Excel Add-in project because people would
have to register the .dll on their computers. Thats about 150 users on a very
secure network. So anyway's I would like to capture the events when I open up
the excel app from VB.NET and also for the users contructing the excel file,
give those folks user defined functions somehow. Is this possible?