Phone randomly black screens, forced to remove battery and reboot

I have looked through the site, and it doesn't seem this has been answered yet. Once a day, at some point I pull my phone out of my pocket and it refuses to wake (black screen only). It isn't off, because the power button does nothing. I have to remove the battery in order to reboot the phone. I have looked for an app to help me find the cause (i.e. Log Collector) but it doesn't help because this isn't as simple as an FC, I am unaware when it happens until I pull my phone out. Is there a way to debug/find the culprit? **My info:** Samsung Galaxy Gio GT-S5660, Froyo, rooted **Note:** I am running SetCPU (no profiles) and Tasker, they are suspects but I haven't been able to get an app to give me a continuous log.