Hi Phil
I think I know why ACID didn't work. ACID reads the lists from the various build sites and when you ask it to download a build it then tries to download it. However if there's a time gap between ACID reading the list and you asking for a download it's possible that during that time gap the autobuild process has created a new build. That's what happened in your case. When ACID read the list the current build was 2357 but by the time you asked it to download the current build was 2359.
This is a rare problem - you have to be running ACID at the time that the autobuild process is running, but it has happened once before.
I looked to see if there was an easy way I could detect the problem, but didn't think there was. I'll take another look.