It fails on <AssertPropertyValue target="haloButtonTests.testLabel" propertyName="text" value="This is a test" />, basically it looks like it’s running an example like this  and verifying that the label value is correct. When running  manually it seems to work so to me it looks like the test is bad.
I spent a couple of hours yesterday trying to get it the build to pass. I
upgraded FireFox and saw checkintests pass from the command line but the
full build still failed. I will look into it some more.