But if I try to recursively copy directories to the udf-formatted dvd-ram: cp -r /some/dir /media/cdrecord than after a few seconds the system freezes totally - only a power off/on to reboot is possible.
This won't help you, but DVD-RAM is quite broken for me as well with a NEC 4570 on all kernels I've tried (2.6.15 through 17)
Horribly slow writing, unreadable data, massive slow-downs during burning (no hangs, though)
C.