my car says the right rear door is open but it isn't.

What is your question?

Sometimes this makes the overhead lights/dome lights come on by themselves at random times, even when I'm driving. Mostly, it seems, when I come to a stop at light or stop sign. Also, and this is the main problem....I can't use my security system to lock my car. I can lock it down, but after a half hour or so, the security system seems to think my door has been opened and it sets off the alarm which is a real hassle for me as I live in an apartment and don't always hear it from inside. I get all kinds of complaints from neighbors about it continually going off as well as things i may have in my car are not secure enough if I keep it unlocked to keep it quiet

What makes this problem better or worse?

it seems to be less problematic when the outside temperature is colder

How long has your 2005 Mercury Mariner had this problem?

since I bought the car, used. About 2 or 3 months.