Example to reproduce the bug (using Python trunk):
---
from gc import collect
import _lsprof

def callMethod(obj):
    obj.clear()
    collect()

obj = _lsprof.Profiler()
obj.enable()
callMethod(obj)
obj.enable()

del obj
collect()
---

The problem is that the profiler is still running when exiting 
callMethod() and so it tries to use callMethod context which was 
free'd just before by profiler_clear().