[Zope] Error Type: error / 23 - 'too many files open in system'

[Trevor Toenjes]

Error Type: error
Error Value: (23, 'Too many open files in system')

This error appears on a page being rendered when it and another zclass are
simultaneously being edited.  This is strange and I dont see the relation.

Where can I find docs on errors to research this?  anyone seen this before?
I thought Zope didnt care if a page was being modified...it renders the most
currently saved version, right?

Thanks,
Trevor