Strange PageDown behaviour in presence of folds

Question

I observe the following strange behaviour in Vim 7.3:

When I'm below a fold, pressing PageDown jumps up to that fold, the next few PageDown presses don't move me out of that fold, and only then PageDown actually jumps down the buffer. The fold remains closed during these operations.

When there are no folds, PageDown works as expected.

Is there any way to make PageDown simply ignore the folds?

UPDATE. This happens only when folds are big enough (because presumably PageDown is moving "inside" that fold).

Answer 1

Turns out this behaviour is caused by the window option being set (to an integer value). If I unset it, everything works great.