Here are my findings.
Because modal panel gets called form the page which is included into other pages, it is not rendered correctly. When the link to call a modal panel is included into the complete page( <f:view>...</f:view>) then it's displayed fine.
So, I was wondering is there is a way to trick it. About link is in a toolbar page which is included into every other page in the application.
I guess the question is weather or not there is a way to control jsf-rendering life cycle.
richfaces moves a modal panel to the top of the browser DOM tree. The reason is exactly this issue with IE. Only the very first version of richfaces 3.0.0 does not perform this moving.
So, you saying that in the versions after 3.0.0 this problem is solved. OK. Will update my project with the latest version and see if it will work. Thank you for your response.