4
Was this a fresh installation of 2.5.4 RC1, or did you update an existing installation? If updated, from what XOOPS Version?
Also, could you download the latest version from SVN, and see if it does make any difference (let's make sure that you have all the latest files).
And in case you've updated an existing installation, could you install fresh 2.5.4 RC1 from SVN and test it?