I have an word add in application created in c# which is accessing a web service and is perfectly working if installed outside Program Files folder. the weird thing is that
If you are using VSTO 4 SP1, then you may be running into a problem described in this blog: http://msdnrss.thecoderblogs.com/2011/06/vsto-4-0-sp1-will-cause-a-vsto-addin-to-not-find-its-config-file/ The solution is to change your registry values for your office addin from:
Manifest=”C:\Program Files\\WordAddIn.vsto|vstolocal”
to:
Manifest=”file:///C:\Program Files\\WordAddIn.vsto|vstolocal“