Really annoying to get "There was an error while gathering this information" on System profiler, after hours looking through internet, several try and noresult, finally get it fixed, here is the step.
get from any MacOSX DVD installation using pacifist the original for those file above, copy them from DVD to above directory, remove /System/Library/Extensions.mkext and reboot. it should get it fixed.
I got this instructions from this link, but instead using 10.4.10 DVD (as it said on that page instructions), I am using any DVD that available on my shack, and found iatkos 10.5.4, currently I am running 10.5.8 system, installed through ideneb 1.5.1.
side note : you need to have this SMBIOSEnabler.kext installed on your system too, and edit the contents of /System/Library/Extensions/SMBIOSEnabler.kext/Contents/Info.plist to reflect your system info.