[racket] [Scribble] problem generating PDF

Hi,

Today I made an innocuous change to the PrePLAI document I use for teaching, and, although the html generation is ok, the PDF generation gets stuck. I tried both at the command line and inside DrRacket. Same issue.
Apparently it's stuck in the pdflatex process, but I can't find any log/trace to give a more informative report. 
Is there a known bug with PDF generation (I tried both 5.3.6 and 6.0)? or is there a way I can make the process more verbose to be able to give more useful feedback? (I'm well aware that what I describe here is insufficient to track down the issue)

In case that helps, the document is split in several files, and I can render the changed file without any issue (and get the PDF of that section only). It's the whole document rendering that gets stuck (and still consumes CPU, as per my monitors).

Thanks!

-- Éric