PBEM games locking up in v7.1

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This problem has started since I installed SPWAW v7.1: when I opt to exit a PBEM game and 'play later', the battle will not load when I attempt to restart it...my hard drive tries to load it but freezes up after a minute or so. I checked in the e-mail folder and there's a 'email#.new' file for the affected battle (in addition to the 4 regular files); if I delete this file the battle reloads, but starts from the beginning of my turn, *without* a security violation warning! This problem happens every time (not intermittent), and when I try the same thing in my installation of v7.0 it never occurs. Has anyone noticed this or know how to fix it?