consistant error message

[elfin]

Have 2.6.7 on osx 10.9.2.   Getting error message shown below everytime I try to use selection A B.    This message occurs when I click on B.  Can't go beyond this message.  Any suggestions?

[mean]

Might have been fixed in 2.6.8

[ZeodyScott]

One thing worth checking is whether the source file itself has any unusual encoding or variable frame rate issues. Avidemux can sometimes behave differently depending on how the video was created. Trying a short sample clip can also help narrow down where the problem is happening.