It seems that my machine and /386/pbs don't get along too well. I reformatted my 9fat partition this way:
disk/format –b /386/pbslba –d –r 2 /dev/sdC1/9fat /386/9load /386/9pcf /tmp/plan9.ini and then my machine booted nicely. Reformatting it again this way: disk/format –b /386/pbs –d –r 2 /dev/sdC1/9fat /386/9load /386/9pcf /tmp/plan9.ini broke things again. Can anyone give me a hint about why that could be? As far as I can tell, /386/pbs and /386/pbslba haven't changed since the 20071222 iso, yet things worked for me after a default install back then, and now they don't... Sander.