ok....RIPLEYS'S BELIEVE IT OR NOT, but i found the issue and will post it here, although it may be very template specific as far as I understood....
I approached this issue just by trying out...so after numerous attempts I found out it must had something to do with the footerbg.gif image (as this was always shown instead of /index.php&main_page=xxxxx) and looking in my folder where this images was supposed to be I saw that I changed the name of the image as it was the logo of ichoze Atheme, a template I was using....but as you can see nothing to do anymore with Atheme....still would like to say THANK YOU TESTUSER as without your template I would never ever designed my website.
Anyway at the end of the day (not just literally) I looked up the respective footer files and finally the solution...the stylesheet.css
I guess in the line where the footerbg.gif was commented there was a conflict or error which was causing this strange behaviour in WHO'S ONLINE...I dont have any idea how the image can be connected with who's online, but just deleting the footerbg.gif-comment in stylesheet.css resolved the issue!!!!:clap::clap::clap::clap::clap:
I am just writing this in case anybody has similar issues. I found some issues googleing around but actually without any real solution. Same problem, but different solutions and any to do with another, so maybe this solution is just for my case....
thanks anyway...
regards,
kruna