[Matplotlib-users] malloc error on show() oder x/ylabel()

i'm running python 2.7, matplotlib-1.0.1, gcc 4.2.1 and grortran 4.2.1… when invoking (successful importing import matplotlib.pyplot as plt) plt.show() in combination with plt.xlabel or savefig("fig.ps") give me that nasty malloc error:

Python(19725,0x7fff7055fca0) malloc: *** error for object 0x102d8c6c0: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap

calling plt.show or x/ylabel("string..") alone doesn't get me that error…

cheers,
hannesk