[mohitnarula]

I had this problem from last couple of days and what I figured out is that the problem was in the Phone nothing to do with the SIM CARD. Now this is how is FIXED this issue:

(This will remove everything from your phone and will give a Blank phone as you had when you purchased it). If you wan't your data back then you can go from Step 1 otherwise if you want the whole new phone Skip to Step 2 and that's it!

1. BACK UP or SYNC your phone via installing Nokia Ovi Suite at your Laptop/PC and then disconnect the phone.

2. Go to Settings, Phone, Phone Management, Factory Settings, Delete Data and Restore.

3. Now you'll get you're new phone. If you wan't you can Restore all you data back by connecting you phone again to your Laptop/PC and do Sync OR you can use a Fresh phone now!

THIS IS WHAT I DID, AND MY PROBLEM IS RESOLVED NOW! 

[AndrjuhaK]

I had this problem last day. I did exactly what 'mohitnarula' suggested.
Few comments on that. After I deleted everything from my phone the problem was resolved. However, I decided to restore last back up and problem came back. So, I deleted again and phone works fine again.