Disappearing scroll bars

Hi, I have a new MacBook Air running Lion, and the new Lion hard-to-see scroll bars are driving me NUTZ. I use the Air in my office with an external monitor, KB and mouse, and although the scroll bars are darn hard to see, at least they are always there.

But when I disconnect the Air from the externals, and just use the touch pad and built-in display, the scroll bars start disappearing all the time. It is worst in Mail, where I have to re-size the window every time I want to scroll. In Safari, they come and go. Re-starting the Air brings them back for awhile, but then they disappear again, until I re-size the window.

Any idea how to get permanent scroll bars?

Thank you!