Bug#416889: Problem identified and solved with a workaround.
I just isolated the problem (at least it seems so...): everything works
disabling hardware acceleration in Options.
Actually, I first deleted .openoffice.org directory in my home and
everything worked fine; then I enabled hardware acceleration and OpenGL
drawing and Impress begun to crash again; disabling hw acceleration (but
keeping OpenGL) the problem disappeared.
I hope can be useful.
Anyway, sorry for the alarm, if unjustified...