If you attach windows debugger to a .Net framework application, occasionally you may see debug spew of unknown exception 0xe0434f4e.

(cfc.1244): Unknown exception - code e0434f4e (first chance)

0xe0434f4e is defined as EXCEPTION_HIJACK.

(Copied from Rotor 2.0 sources corexcep.h)

#define EXCEPTION_HIJACK  0xe0434f4e    // 0xe0000000 | 'COM'+1

EXCEPTION_HIJACK is thrown by CLR as part of the process of suspending threads for garbage collection. It's raised to help resume execution after a suspension.