Hi TIG,
The following is the whole error message:
"Error Loading File pushpull_tool.rb
can't convert nil into StringError Loading File push_pull_vector.rb
can't convert nil into StringError Loading File push_pull_z.rb
can't convert nil into StringError Loading File quick_selection.rb
can't convert nil into StringError Loading File script_loader.rb
can't convert nil into StringError Loading File selection.rb
can't convert nil into StringError Loading File thicklines.rb
can't convert nil into StringError Loading File utilities.rb
can't convert nil into StringError Loading File weld.rb
can't convert nil into StringError Loading File XrefManager.rb[/color]
can't convert nil into StringError Loading File ZLoader__FredoScale.rb
can't convert nil into StringError Loading File ZLoader__OnSurface.rb
can't convert nil into StringError Loading File dynamiccomponents.rb
can't convert nil into StringError Loading File langhandler.rb
can't convert nil into StringError Loading File make_pano_pm.rb
can't convert nil into StringError Loading File sandboxtools.rb
can't convert nil into StringError Loading File SolarNorth.rb
can't convert nil into StringError Loading File webtextures.rb
can't convert nil into String"

I couldn't make the Ruby Console open before the error message showed up. If this is not what you were looking for, please guide me to get there.
Many thanks,
PS

Hi TIG,
This was how the errors showed up when the loading of Xref Manager V5.1 was failed.
"can't convert nil into StringError Loading File XrefManager.rb"
Thanks for helps.
PS

Hi TIG,
I just upgraded my SketchUp to V8 Pro but the V5.1 is not working anymore. I can get an advice to fix it?
Thanks,