Janko,
That error "Error: Attempt to evaluate a block that is already being evaluated" came up again and so I decided to take a look. I'm almost certain the cause is that you defined a #startUp method on SpEnvironment class that is meant to be executed whenever the image starts up. This is fine and good except that the way this mechanism works a message #startUp: with a boolean argument indicating whether or not this is a true startup (aka resuming) indicated by true, or whether this is simply after a snapshot is made, indicated by false, is sent. Sort of odd I guess but the same mechanism is used for quitting and snapshotting. Behavior defines #startUp: to simply send #startUp and so your existing implementation worked but it was also being called after a snapshot and not a true restart.
So I defined #startUp: on SpEnvironment class that only takes the action if the argument is true. I left the old #startUp for now, though it should no longer be used and I left a browser open on the added method so you can look at it and modify as appropriate if you like. I did not update any packages so you will want to take care of that also.
Ken
webteam@lists.squeakfoundation.org