problem with multiple execution of Avidemux

[jsk]

I have a problem with the win64 nightly builds:
I once installed r8411 with a win64 setup from avidemux.razorbyte.com.au.
With this "setup version" it is no problem to start several instances of Avidemux and encode more than one movie at the same time.
When I replace the installed avidemux with the unpacked content of a nightly build, Avidemux works fine if I start it only once. If I start it twice (or more) the both instances seem to block each other and the execution becomes extremely slow and it seems they will not finish in finite time.
This behaviour does not depend on the version of the nightly build. It happened with every nightly build I tried and it does not happen with a setup. Unfortunately there are no more 64bit setups of Avidemux 2.6.4.

Does anybody know the reason for this behaviour?

[mean]

Are you running the _portable version or not ?

[jsk]

Are you running the _portable version or not ?

no it's not the portable version