Raver, it's also worth checking to see if your computer has automatically updated any device drivers recently. I recently had an issue when USB drivers were updated and it stopped a different Python-based application from running. You should also double-check your Windows Update history — fully expand everything (especially the drivers section) and make sure there's nothing saying "failed" in there. If there is, attempt to reinstall, and then reboot even if it doesn't say a reboot is required.
Failed Windows Updates are a major cause of "my non-Microsoft application just stopped working!" errors. A reboot alone won't fix it, nor (usually) will just fixing an environment variable; if an update has failed, that creates cascades in the Registry. Rather, it creates avalanches in the Registry.
It could be something else, too, but this is worth ruling out.
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