Users with polish keyboards cannot input some data in the Rich text Editor of the Content editor webpart or the Wiki pages

Polish has letters in addition to the 26 letters that are used in English. However, you cannot type some of these additional letters in the Rich Text Editor. For example, this issue occurs when you try to type some Polish letters in a blog or in a custom list that uses the Rich Text Editor.

We need to run the STSADM utility to enable this fix. Use the following command:
stsadm.exe -o setproperty -url http://portal -pn “richtexteditorshortcutenabled” -pv “no”

This has to run on the portal which contains the site collection.

Reference article : http://support.microsoft.com/kb/942388