I've had a number of games that don't like my dual core. I used to use imagecfg to permanently set affinity to 1 core for problem games.
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But it makes a change to the exe and that recently caused a problem with one games copy protection.
This link has a number of possible solutions. I went with the hot fix and haven't had any problems since. But it is an unsupported hot fix, so use at your own risk.
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