TinyMCE 2.2 and pop-up to browse server

[mev]

I installed CMS version 1.1 and TinyMCE 2.2. that came with it (basic module). Having persisting problem though, driving me mad:
the button of TinyMCE to browse for a file or picture, nor the HTML-button,  work at all, nothing happens!
Not in IE 7, in IE 6, nore in Firefox 2.0.0.6
Sometimes  I get an error saying "Callback function "TinyMCE_SimpleBrowserPlugin_Browse could not be found"..
Set all rights with chmod for the directory modules on 775 at least.
Sometimes it works right for 3 or 4 times, and then again nothing...

I un-installed, deleted and re-installed the basic version of Tiny... same problem
Emptied caches inside CMS, no difference

Two weeks before I installed exactly the same versions of CMS-Made Simple and TinyMCE 2.2. basic for another site at another server, but that one works well!!!!!!! Tiny does browse to pics of fils and opens the html-button!
FCKeditor does work well too at both servers.

Is anybody having same sort of problems ?
Or could anybody give a clue in which direction I should search, please???

Willemijn