That's probably because you had IE6 installed. My advice is to install latest IE6SP1 cumulative update; if you can't install it, extract it and replace dlls in \windows\system with dlls from it.
It won't work with KernelEx 0.3.5, because there are not all things implemented in PSAPI.DLL However, here's PSAPI.DLL with that stub: http://tihiy.ahanix.org/psapi.zip Try it alongside with latest KernelEx.