[HLUG] gnucash hijacked .gz files

[Gordon Alabaster]

Hi,

When I double click a file with ending .gz, gnucash tries to open it.
How can I reset this so that all .gz files default to opening with
Archive Manager? 

I can reset the 'default open with' for individual files in properties
but can I make a blanket change somewhere, because I can't find where.
I'm running Ubuntu 8.04 and Gnome.

Gordon.