About:config settings change by themselves when switching between windows/linux on dual-boot machine with profile shared between OSs

Question

I dual-boot ubuntu and windows7, and have set up firefox to use the same profile data when running under either OS. This works great, except:
(1) each time I switch OSs and start firefox, it runs the "checking add-on compatibility" test (which is a minor annoyance)
(2) each time I start firefox in ubuntu after recently using it under windows, the about:config setting "browser.backspace.action" gets reset from my preferred setting (0) to the default setting (2).
How can I prevent these two things from happening?

Answer 1

Maybe it is better to use separate profiles for each OS and create symlinks or hard links to the sqlite databases that you want to share.
Your Linux profile may be using extensions (e.g. Ubuntu Firefox Modifications) that modify specific settings and in such a case you can't really prevent this.<br />
You can use a user.js file to initialize specific prefs on each start, but that makes it impossible to make changes on the about:config page that last the current session and you need to remember which prefs are affected.