One-Click Advanced mode has disappeared

I’ve been working with a Wordpress site for years now, installed using one-click advanced mode.
Now I want to add another Wordpress install, but advanced mode has disappeared from the on-click install screen. What happened?
In essence: I want my one-click advanced mode back! What went wrong?

Can you post a screen shot of:

It’s still there for me, so it’s really strange that it’s vanished for you.

Solved. It was because the domain was still PHP4. Nobody knows why the problem appeared just when it did, though.