Problems running M2Crypto tests ...

I am attempting to run the M2Crypto tests with limited success.  The command 
'python setup.py tests' doesn't work, and so I have being doing 'python 
tests/alltests.py' to run the supplied test suite.

I have been running this in 32 mode on various boxes and in virtual machines.  
These run just fine.  But when I move the code over to a 32 bit OS hosted in 
a Xen VM the tests fail.  The output starts with a couple of '....' in the 
output, but then starts errors with 'EEEEE'.  If I am not quick to kill it at 
that point it eventually exhausts ram and the VM crashes!

I can't see any reason why everything would work anywhere except in a Xen VM, 
does anyone have any ideas or has anyone seen this behaviour before?

Bill