Thread:Project:Support desk/Profiler.php Fatal Error Cannot redeclare wfprofilein()/reply (5)

I'd be careful deleting core files rather than tracking down the core problem. If for no other reason than whatever is causing the error probably isn't working now anyway and is likely to unnecessarily drain your resources. A good strategy is to disable your extensions one by one (or groups at a time if you have a lot) to locate the source of the problem. Then try downloading the release branch version of that extension, and if still no luck, the trunk release. While some developers only use the trunk release directory, others are already using it to test MW1.19, which is causing problems on MW1.18 installs using SVN to pull from the trunk.