convert-u5data error

[eeknay]

I'm importing Urchin 5 reports into Urchin 7 and a few of my profiles bomb out when running convert-u5data, specifically in the "converting sessions" step.  Happens every time, consistently on the same months of data, even after running the sanitzer.  Anyone have any insights on what could be happening here?

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Convert-u5data 7.100 (win64) starting: 20121115 10:00:42

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[10:00:42] Converting profile: pcfweb

  Converting 201101

Converting totals...    done

Converting histograms and matrices...   done

Converting log tracking records...      done

Converting data records...      done

Converting visitors...          200 (100%)

Converting paths...             51933 (100%)

Converting sessions...

ERROR: Received interrupt signal(11)

[Angelfish Stats]

Which visitor tracking method does the profile use in Urchin 5?