[JKT]

With the exception of the AppleIntermediateCodec.component, I would temporarily move all other QT components out of the folder, restart and see if the issue persists. Then check to see if you have all the latest versions of each component. Personally, unless you are encoding media as divx .avi files, I would not re-install the DivX and xVid components and would instead install Perian.

Edit: when OmniWeb crashes, does the log for the thread that crashed give any clues as to which codec could be the problem, if any?