I now have eBL 3.0 running nicely on two Macs - desktop and notebook.
The second installation warned me I had used six out of six of the maximum authorised reader / computers. Prior to today I had been using various Fusion virtual machines, and I had been a bit sloppy at clearing up after myself - virtual machines are *so* disposable!). I trawled through my various virtual machines, selecting "Manage Devices" from the "My Account" pane of eBL 3.0, deleting the surplus authorisations.
I was left with one, which must relate to a virtual machine I long since trashed. I renamed it "SONY support - pls delete me!!", raised a ticket following the "Can't access that computer anymore?" link in eBL and the subsequent several steps on the Sony website.
I got an immediate acknowledgement at 19:57 and a confirmation that the rogue authorisation was deleted at 22:50. Terrific service, and I now have three vacant slots. Very handy in a family of four
Kudos to Sony. Mac users have overnight been elevated to the status of real people! I know some forum members still have some issues, but by and large I think this a great step forward, and Sony have done a good job. Just wish I could decide between a 600 and a "900"! Whatever, someone in the family is getting a second-hand eReader for Christmas!
amjb