Energy Saver preferences keep breaking

This is a new question related to a question I asked previously.

MacBook is sleeping despite being set to "never" sleep

Basically, the MacBook would sleep after 3 hours despite the preferences telling it to "never" sleep.

I fixed the original problem by deleting the Energy Saver plist file.

However, after two weeks, it broke again and the original problem came back. I have no doubt that I can just fix it by deleting the preference file again.

Obviously something external is botching up the Energy Saver preference file. I'm wondering if anyone can tell me how I can determine what could be causing this problem in the first place.

EDIT:

Trashing the Energy Saver plist file no longer fixes this issue. I've removed Caffeine and I'm out of ideas. I can't even effectively troubleshoot this since it takes three hours just to see if it will sleep or not. What else can I do? Where else can I look?

Solution 1:

Perhaps you should try resetting the SMC, as described here: http://support.apple.com/kb/ht3964