Here is an excerpt from a boost test run where an exception occurred:

<Info file="/var/lib/hudson/jobs/ColdAtom/workspace/trunk/grain/test_model.cpp" line="247">check m->field_known() passed</Info>
<Exception>memory access violation at address: 0x00000008: no mapping at fault address<LastCheckpoint file="/var/lib/hudson/jobs/ColdAtom/workspace/trunk/grain/test_model\
.cpp" line="247"/></Exception>
<Message file="./boost/test/impl/unit_test_log.ipp" line="164">Test is aborted</Message>
<TestingTime>2950000</TestingTime>
</TestCase>
</TestSuite>
</TestLog>

Then the hudson log:
[xUnit] [WARNING] - The file '/var/lib/hudson/jobs/ColdAtom/workspace/test_model.xml' is an invalid file.
[xUnit] [WARNING] At line 1 of file:/var/lib/hudson/jobs/ColdAtom/workspace/test_model.xml:cvc-complex-type.2.4.a: Invalid content was found starting with element 'Exception'. One of '

' is expected.
[xUnit] [WARNING] - The file '/var/lib/hudson/jobs/ColdAtom/workspace/test_model.xml' has been ignored.

Boost test also inserts message tags which will fail to parse. This will happen when a unit test has no assertions. It would be nice if these errors would break the build at least. I do have "Fail the build if test results were not updated this run" checked, but it ignores the test and the build succeeds.