If you just turn off the favorites bar, quit the application, and relaunch, it still comes back with the favorites bar? That's pretty weird...do any other preferences you change also fail to stick?
Quit OmniWeb (use OmniWeb->Quit OmniWeb, closing all the windows is not sufficient)
Launch the Terminal application
Type the following line, followed by the return key:
Code:
defaults write com.omnigroup.OmniWeb5 BrowserFavoritesVisible false
That will change the preferences file to indicate you don't want the favorites bar showing. If it still shows up after doing that, either you did it wrong, or something is messed up on your system. I'd try creating a new user and see if the behavior persists there in that case.
I check the "auto-save while browsing" box at the bottom of the Workspaces window for my default workspace and OmniWeb always puts my windows back the way they were when I quit.