I have done a quick update to 2.0.23 to 2.0.24-rc1 which fixes the Firmware Install and AutoUpdate checks.
The backend servers are now updated for different regions to improve download speeds, this requires changes in AP2 to accept redirects of FW images downloads. 2.0.24-rc1 fix this.
Downloads available from
http://firmware.us.ardupilot.org/Tools/APMPlanner/beta/
I hope to release 2.0.24 as a stable release this week. Please let me know any issue you have ASAP.
Thx