Error: This application has requested the Runtime to terminate it in an unusual way

Hello,

I have the following small problem when terminating a matplotlib script.
Basically I do the following (interactive set to False):
from pylab import *
plot([1,2,3])
savefig('bla.ps')

Now, this script does produce the PS file but then terminates with the error message:

>Fatal Python error: PyEval_RestoreThread: NULL tstate
>This application has requested the Runtime to terminate it in an unusual way.
>Please contact the application's support team for more information.

I know that I could use the PS backend which avoids this problem, but I want to be flexible and either generate a PS file or some screen output and so I keep the default backend.
Since the script actually does what it should do the question is somewhat aesthetical:

How can I avoid this error message ?

Many thanks,

               Axel Kowald