Same problem on portable version as installed version.
Quad core cpu, 4 gb ram, Win Seven 64bits
Video file info attached.
The main release is fairly old now. There have been a lot of bug fixes. Try the most recent "nightly" Win64 build:
http://www.avidemux.org/nightly/win64/
Dan.
Apart from that, "not responding" is not an error. If the most recent nightly build still exhibits the same issue, please compress and attach admlog.txt from %localappdata%\avidemux\ folder from the Avidemux session with the "not responding" message.