There is a small bug with that release that makes it not find ui.xsd, you can fix it by going into options and removing the trailing '\' from both the directories listed there. You probably have:
WoW Install Directory
C:\Program Files\World of Warcraft\
Work Directory
C:\Program Files\World of Warcraft\
|
it needs to be
WoW Install Directory
C:\Program Files\World of Warcraft
Work Directory
C:\Program Files\World of Warcraft
|
to work correctly. I will have another version out soon that fixes this anyway. Note that in order to use the designer with 1.10 patch, you need version 1.0.300.2 otherwise you get lots of errors due to it not recognising the new Font elements. Also, you no longer need to uncheck Verify Blizzard Files option.
Thanks
Nulk