problem with packet-writing and pdflush

Hello, when I use packet-writing (latest patch for 2.6.6) on my dual PIII system, pdflush sometimes uses up all CPU-time and the system hangs. I'm using kernel 2.6.7-bk6 and try to write to DVD+RW, which is quite ok as long as write rate is small (Capturing video to DVD, copy of small files). Copying larger files (~600 MB) to the DVD (using cp) still works without crashing the system, but the problem with pdflush is already visible; the system hangs for short periods. Copying multiple larger files leads to a complete system crash. Any idea what I can do to avoid this? I can supply more information(kernel config, drive type ...) if needed. Regards Georg Chini