Something strange is happening in my Windows Debug builds (fresh CVS tree) If you remove "urllib.pyc", and execute 'python_d -c "import urllib"', Python dies after printing the message: FATAL: node type 305, required 311 It also happens for a number of other files (compileall.py will show you :-) Further analysis shows this deep in the compiler, and triggered by this macro in node.h: --- /* Assert that the type of a node is what we expect */ #ifndef Py_DEBUG #define REQ(n, type) { /*pass*/ ; } #else #define REQ(n, type) \ { if (TYPE(n) != (type)) { \ fprintf(stderr, "FATAL: node type %d, required %d\n", \ TYPE(n), type); \ abort(); \ } } #endif --- Is this pointing to a deeper problem, or is the assertion incorrect? Does the Linux community ever run with Py_DEBUG defined? I couldn't even find a simple way to turn it on to confirm it also exists on Linux... Any ideas? Mark.