One Page = One Minute?

If you're using 12pt courier, the page/minute you have is right. No need to change.

There should be a page number function too. It's an option.

I don't have it installed right now so I can't check, but I had the same issue myself until someone told me.

I'm using celtx as well and if you look at the bottom there is a typeset tab or there should be and that automatically properly formats it into pages for you.

The one page = one minute is a general rule but remember one page of action can be a couple of minutes and a page of dialogue can be over in 30 seconds.

Single spaced 12 point Courier New with proper formatting should give you an average of 1 minute per page BUT if it's a talky-talky then probably less and if it's all out action then probably a lot more as others have said. It's just a rough rule of thumb.

A 67 page shooting script sounds impossibly short but that can easily clock out at 96 minutes of film. I wouldn't write a 67 page spec script though.

Likewise a 110 pager can come in at 88 minutes.

Also depends on writer's style: some more wordy in narrative than others.

90 pages is the traditional 'minimum', (remember: no rules if it's great!!) and I wouldn't go much over 130 pages even if it's dialogue-heavy (quick banter rather than long Tarantino-esque monologues).