Crash on Insert Measure command

Writing a cadenza for a concerto, I created a 60-beat-long irregular measure, but then wrote more material than would fit. In order to get it all in one measure, I intended to insert a new blank measure, then set that one as irregular and for the number of beats needed, then copy/paste the material into that single measure.

However, everytime I right-clicked on a measure--even a regular one--and then clicked on INSERT MEASURE, the application crashed.

Here is the text of the error detail:

Problem signature:
Problem Event Name: APPCRASH
Application Name: mscore.exe
Application Version: 0.0.0.0
Application Timestamp: 512df23e
Fault Module Name: mscore.exe
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 512df23e
Exception Code: c0000005
Exception Offset: 00041ab8
OS Version: 6.1.7600.2.0.0.256.48
Locale ID: 4105
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

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Has anyone had this happen; and does anyone know of a solution or work-around? I am using MuseScore 1.3.

Thanks