This was a common occurrence in cm10.1 with TWA_priv's build I believe. This is called a Sleep of Death or SoD. I thought that was cleared up, but maybe not. If there is a newer version of the ROM that you are on, I recommend trying that. There is no way to recover from an SoD except to force power off like you did, and start back up.
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Current: Nexus 7 running stock 4.4 (CM11 soon)
Retired: Kindle Fire running Jellybean CM10.1 / Android 4.2.2