Screen Timeout...What do you set yours on? Please help?

[Chesapeake]

Hey everyone. I'm hoping someone can help me here. I have my phone set to 30 seconds and I am using Screebl. But when I am on a phone call and I take the phone away from my face either to hang up or access the dialpad or mute, it goes black so I often can't do anything. I can't even hang up sometimes. Ideas?