I don't know exactly why this error appears sometimes, but certainly i see this behavior when the Category or Section have spanish characters like accents (like the word "Canadá" or "Últimas Noticias") or ñ.
I experiment this issue when I loaded a pre-builded article, and the message appears, but load the contents with no troubles, but when I published the page, the result is not an updated version, but a blank page instead.
The test was done in:
Win XP SP2 Joomla 1.0.12 Blogg-X 2.0.13 Java Machine installed using the default downloader of Blogg-X