Noob problem with HDR video frames going bright 4 stops

[Jim O]

Hi,  I just installed V2.3 on my 5D2 to use HDR video for real estate shots.  I got ML installed and was able to process video using interframe script.  I put C frames in FCPX and everything looked great. I started experimenting with varying ISO levels, and was using 100, 3200, which seemed to work well.  After trying several times, suddenly after 1-2 sec of video, the exposure level of images in video would jump 3-4 stops and everything got very bright.  This happened repeatedly and the only way to fix was to reformat card, erase ML and re-download and install ML.  I am wondering if this has happened to others and if this a known issue and if there is something I should watch out for.  Thanks in advance for any help.