Deleting differential backups of files causes crash of TIH 2014 Build 6673

Windows 7 64 bit. Acronis True Image Home Premium 2014 Build 6673. After first complete backup I am making only differential backups of certain files and directories on my PC harddisk to a NAS in my home network. Making the backup works. I want to delete differential backups deliberately depending on NAS capacity. Goin to Recovery gives me the array of backup dates in the bottom of the screen, but when trying to delete one out of the series the program lately crashes giving these data before succumbing...
Problemsignatur:
Problemereignisname: APPCRASH
Anwendungsname: TrueImage.exe
Anwendungsversion: 17.0.0.6673
Anwendungszeitstempel: 52f10615
Fehlermodulname: TrueImage.exe
Fehlermodulversion: 17.0.0.6673
Fehlermodulzeitstempel: 52f10615
Ausnahmecode: c0000094
Ausnahmeoffset: 00279e73
Betriebsystemversion: 6.1.7601.2.1.0.256.4
Gebietsschema-ID: 3079
Zusatzinformation 1: 0a9e
Zusatzinformation 2: 0a9e372d3b4ad19135b953a78882e789
Zusatzinformation 3: 0a9e
Zusatzinformation 4: 0a9e372d3b4ad19135b953a78882e789

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Any idea how to solve this problem?

Franz4700