My Bold will intermittently require me to login. I have done a SIM swopout to try and fix the problem, but it has not cured the problem. Any suggestions?

login to what?

Hi, the login to the service provider is dropped neccesitating me to re-enter my Pin to re-establish service.

What service provider? Where are you entering your PIN? What does the login dialog specifically say?

The Service provider is Vodacom. The Pin code entry prosedure is exactly the same as when I switch on the phone and am prompted to enter my Pin code, the only difference is that it switches to this mode when the phone is on!

Do you get a message that says "Device is locked" that has buttons for "Unlock," "Emergency Call," and "Cancel?"

No, just the normal enter pin with a notification that I have 3 chances to get it right.

That sounds like SIM lock. Go to Options, Advanced Options, SIM Card. From there, hit the menu button, and there should be an option to disable security.

Sounds like SIM Lock, but if you're constantly having to re-enter the SIM lock code then something else is going on (like your BB is power cycling off/on). Disable SIM Lock, and keep an eye on the phone. Is it truly intermittent, or does it happen the same time every day, like when you sleep it's on and ok, and when you wake up, you need to re-enter the code?