likely something like:  http://codex.simple-press.com/codex/faq/troubleshooting/what-is-this-jquery-conflict

but hard to say without a link…

and all browsers run different js engines so sometimes why it only occurs in some…  which IE browser? versions IE 8, IE 9 and IE 10 are supported with of course IE 10 offering the most standard experience…

HI again

Thanks for your link, I will try to read it and understand.

Meanwhile: The problem occurs in both IE 8 and 9.

Link to our forum is here: http://www.viaretro.com/forum/

Any other buttons not working? 

the reply button opens a hidden area and then scrolls to it… if a js error has already occurred on the page, it may inhibit the open/scroll js from working…

When visiting your site with IE 10, 9 or 8, I dont see any errors of concern, but I cannot test a reply since guests cannot post…

If you want to see if its a conflict, you can run couple tests… try a temp switch to wp default theme – does it work?  if not, disable other plugins and try again… does it work?  if so, enable plugins one by one until it doesnt work… then we know if conflict…