Collapsible Text only works ONCE

Hi
I urgently need collapsible text in our intranet (Drupal 5.7 with CCK and Views), but I experienced the following effect:
- Installation of Module, config of filter - everything ok and the collapsible text works.

BUT if I quit the actual page with collapsible text built in and come back to the page it does not work at all.

What I did to figure out the reason;

- Disabled all other filters
- Tried another Theme
- Disabled all modules which seem to bring in javascript conflicts
- Checked the forum

But still the same effect.

Any idea what the reason could be?

Thanks for a quick hint.

Cheers, Rolf