It seems that Nautilus doesn't have the usual headings under 11.04. I'm used to selecting Edit > Preferences > Behavior and then choosing single-click. How do we enable single-click in 11.04?
Sounds like it might be a bug. I'm installing Natty now, but in the meantime, it might be worth trying this. Press Alt-F2 to open a run dialogue and enter
Now scroll down to apps/nautilus/preferences and try altering the click policy there.
I've attached a screenshot.