I found it. Debugger attached to explorer, prior to viewing folder: 0:016> u kernel32!isdebuggerpresent kernel32!IsDebuggerPresent: 7c813123 64a118000000 mov eax,dword ptr fs:[00000018h] 7c813129 8b4030 mov eax,dword ptr [eax+30h] 7c81312c 0fb64002 movzx eax,byte ptr [eax+2] 7c813130 c3 ret 7c813131 90 nop 7c813132 90 nop 7c813133 90 nop 7c813134 90 nop 0:016> !chkimg kernel32 -d 0 errors : kernel32 I then input "g" to let the debugee run, and proceed to view the folder, then Ctrl+Break. 0:016> !chkimg kernel32 6 errors : kernel32 (7c813123-7c813128) 0:016> u kernel32!isdebuggerpresent kernel32!IsDebuggerPresent: *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Program Files\Combined Community Codec Pack\Filters\Mpeg2DecFilter.ax - 7c813123 e90894ea86 jmp Mpeg2DecFilter!DllUnregisterServer+0x40 (036bc530) //[b]here it is![/b] 7c813128 cc int 3 7c813129 8b4030 mov eax,dword ptr [eax+30h] 7c81312c 0fb64002 movzx eax,byte ptr [eax+2] 7c813130 c3 ret 7c813131 90 nop 7c813132 90 nop 7c813133 90 nop However, start/shutdown does not crash explorer immediately upon viewing of the folder though. This is what I am confused about. Any ideas?