Hi,
You should be using a slightly different format for the macro in the where condition of the repeater:
NodeGuid='{%cmscontext.currentdocument.nodeguid%}'
Note that this does not go in the transformation itself, but in the repeater that's using it.
Tip: when looking at the 'where' condition of the repeater, if you click the little black arrow to the left of the textbox, you get a popup Gui macro-building tool where you can build a macro that'll get you the information you want, in the proper format to use. FYI - I used the macro-Gui tool to build the example above.
Tip #2: And if you look in the site manager > administration > event log, you'll see more info about your error.
Lance