auto screen lock not happening anymore

[carteriii]

When I first got the phone, anything that turned off the screen (explicitly or simple timeout) would require me to slide the screen lock left or right when the phone was next turned on. Somehow, I've lost that functionality. Now the phone doesn't require me to unlock it unless I explicitly lock it. A friend who also has the Imagio still has the automatic screen locking functionality, so I don't believe I'm just making this up.

I do not have a password set, using the Lock settings, but I never did. I also don't see anything else in the Lock settings about an automatic lock.

I have installed a few apps, but didn't pay attention enough to know if it was something specific. I'm hoping someone here might know of a simple setting that I just have to reset, otherwise I'll need to go uninstall various applications with the hope that I figure it out.

Thanks in advance.