your outlook throw the above error when you click an hyperlink in your outlook message, there is nothing to do with the group policy eventhough the error looks like gp mismatch..
This error comes when your system get confused about the default browser of your windows. There are two locations you need to look at...
Set IE as your default program
To set IE as your default program, go to Control panel > default programs > set your default program. Then click on internet explorer and click on set this program as default.
Restoring REGISTRY settings to default
After setting up IE as your default browser your need to restore the file association of .html, .htm, .shtml, etc.. This can be done in registry, Let's see how to do that.
Type regedit in run and hit enter. This will launch registry editor. Expand HKey_Local_machine > Software > Classes find and select .html, in the right pane double click on default and change the value to htmlfile, then give ok. The default value might have been changed if you were having any browser other IE previously.
Do the same for .htm, .shtml, .shtm to restore their association to default.
Feel free to contact us, if you find any difficulties. Hope this helps..
Techytips