Error in IPython Shell

I've just started playing around with IPython, and it's got some pretty cool features. I especially like that it "remembers" input from previous shell sessions. I am having some trouble, however, with the tab completion.

Here's an example of my console:

In [5]: a.__class__.python(58387,0x7fff70630c20) 
malloc: *** error for object 0x103133b40: incorrect checksum for freed object - 
object was probably modified after being freed.

*** set a breakpoint in malloc_error_break to debug
Abort trap

a is a strin开发者_开发技巧g, and I've typed a.__class__. and then hit TAB and this is the result

Has anyone else had this problem? Any fixes?

Thanks