Sorry for such big delay, i just want to clarify in case someone else finds this post and might get the wrong idea.
The stylesheets list is the minified css sent to the browser. It includes all my css files minified by the CSS/JS Loader thus saving precious load time.
The tpp.css comes from tabbed products pro, the tabs on my product page.
I solved my problem editing the stylesheet.css where there were some confilicting width's. It took me some time, but i found the web developer plugin for firefox which helped a lot. It now works good, as far as i tested, on IE 6,7,8, FF, Opera, Safari and Chrome.