My blackberry is giving me the jitters

Guys, have you faced continuity issues with Blackberry. Mine is 15 months old and it is giving me some problems.

1. The antenna doesn't work properly. It continuously searches for network in places where it didn't previously
2. The 'saved messages' folder seems to have lost a number of messages. For instance, a whole set of messages between certain dates have gone missing.
3. The IM chat sessions take ages to open these days. I haven't changed location nor have I changed what I used to do previously
4. The button that on pressing displays "Entering stand-by mode........" doesn't function all the time.
5. The call quality has deteriorated. The sound fidelity seems to have gone down.

Let me know if any of you guys are facing similar problems.