[XeTeX] XeTeX quits typesetting with "broken pipe"

[Pierre Funck]

Hello,

I'm working on a book project with a lot of figures and with OpenType 
fonts loaded via the fontspec package. XeLaTeX (on MacTeX) stops in 
the middle of the typesetting process with the error "broken pipe". 
The precise place where the error occurs is different every time, not 
reproducible. The error doesn't occur when I switch the graphicx 
package to draft mode. (Tried switching to GhostScript instead of 
pdftex with no success.)

The problem only occurs with XeLaTeX. No error occurs when compiling 
the same file with normal LaTeX (where, of course, I can't use the 
OpenType fonts I need).

The problem only occurs on my MacBook Pro with Mac OS 10.5.2. 
Everything seems to be working fine on my PowerMac G5 Quad with Mac 
OS 10.4.11. So it might be a Leopard incompatibility.

Any ideas?

Thanks a lot in advance.
P. Funck