testing 5S RC5

Hi Guys,
When i install for testing 5S 5.1 RC5 64 bit (demo) i have a unexpected error.

excepttion access violation(0x0000005) at pc=0x00000000253e0ba1, pid=6128 tid=3644
do you want to debug the problem?
to debug, attach visual studio to process 6128;then switch to thread 0xe3c
select Yes to launch visual studio automatically (patch must include msdev)
otherwise, select no to abort…
i have the choice yes or no but both are the log out ultramixer.
the current version is working
i have install on a 64 bits windows 7 (I5)

Thank you and kind regards

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