What other apps do you have running/installed on the Mac? I'd suggest raising a bug report on http://bugs.maemo.org/ , however the Mac OS flasher isn't officially supported so it may take a while to fix.

Nothing else running at the time, and all other USB devices unplugged.

I submitted a bug here.

I'm having the same problem under dapper, I've tried memory card in and out, system resets, usb bugfix on the maemo wiki

I just ran the update in Slax with no problems, can be run from the live cd if you have a hard drive to usb key with the flasher and image

I tried using flasher-2 with a G4 running OS 10.3.9 and then a G5 running 10.4.9 . I tried several variants of the above tricks to load the ...49-2 update to OS 2006 for Nokia 770. I consistently got the error "Error claiming USB interface..." immediately after the flasher acknowledged the USB connection to the 770. With the other mac running OS 10.4.9 I ran the flasher via the command: sudo ./flasher-2... -F filename.bin -f -R. It worked with no problem. The "Error claiming..." message was replaced by a message acknowledging connection: "Found device SU-18, hardware revision 1602
NOLO version 0.9.14" Someone else in this forum tried a number of different macs and found some that worked and some that didn't. Theory: flasher-2 assumes a mac with USB-2. if this is true, it should be indicated.