I mounted an NFS exported DVD drive from an HP-UX 11i box on my MacOS X client (using 10.2.4). The mount was ok and I started to copy the contents of the DVD, but exactly after copying 717MB the copy halted and the Finder froze with an ever spinning ball. I couldn't kill processes, because the Terminal program did not start up properly. The Dock still worked (even with all the effects), and I could start some programs, but I couldn't get back to a working Finder or Terminal. The power button still responded and I was asked, if I would like to restart or shutdown, but neither option worked. I had to power down the computer by holding the key for several seconds. I reproduced the problem 3 times, it always stopped at 717MB, no matter if I copied the whole folder or file by file.
The reason for using an external drive was a DVD+RW, which my 12" PowerBook does not read (but a several year old HP DVD-ROM drive, bah).
I looked at the Apple knowledge base, but couldn't find any hints related to NFS problems copying large files.