How to wean Firefox 3.6 to remind me that he updated after the launch of 4.0?

The crux of the matter:
Installed FF 4.0 Beta 4 and 3.6.9. If you use 4.0 and then go back to 3.6.9., in 3.6.9. will thanks for updating "Thanks for ...", show a page with the choice of Wallpaper, which is somehow terribly slow. At the re-opening of course will show the default page (empty).

4 after 3.6.9. also shows the thank you page, but at least she is not so slow.

Question — how to make 3.6.9. normally coexist with 4.0. not showing every time the page update after the upgrade?