I've upgraded to Gnome 3 and the problem I'm facing is that when I restart, sometimes the menus and buttons look old-fashioned like this:

whereas sometimes, it looks modern and neat like this:

Notice the differences between the two: here are a few differences:

1. The menu bar (notice the difference in fonts, dark grey color of Snapshot1 vs the light grey color in Snapshot2 in the background)
2. The file navigation bar bellow the menu bar (notice the 'Home' button there and also the left arrow button)

3. The left-hand side navigation bar (font, background color and color of selected folder)

   The old style look effects the GTK aspects of the interface, such as the menu, buttons, mouse pointer etc. Another observation is that changing the GTK themes does using gnome-tweak-tool when the old style look is loaded does NOT work. However, this works when the regular look is loaded.

How can I ensure that the old-fashioned look does not load on boot?