Code:
int x = -1073741819;
printf("%d = 0x%08X\n", x, x);
-1073741819 = 0xC0000005
It means that Avisynth, or more likely one of the plug-in's you are using, has
crashed - with
STATUS_ACCESS_VIOLATION (0xC0000005) error.
In case of a "hard" crash, you won't get any useful error message, as the program just dies. You may be able to locate in which module and function it crashed using a debugger though.
Anyway, this problem obviously is
not related to x264 or Simple x264 Launcher. All you can do at this point is stripping down your Avisynth script and find out which plug-in is responsible.
[EDIT] And, most important, get rid of the unstable mess called Avisynth-MT for now and try again with a
stable Avisynth
[/EDIT]