Problem with contacts names changing to Uknown while talking to them

jamaicanserb

Hello,

My problem is:

I have my contacts with their names and phone numbers. Problem is when they call me or when I call them it shows their names but when I answer the call it changes to Unknown and when I finnish conversation in Recent calls it also shows Unknown, so I cant look up with who I was talking with or similar.
This problem occurs only with contacts that are in my mobile carrier.

Also, Im having some troubles with touchscreen, sometimes is not precise while im texting, I installed SGS Screen Booster and wrote parameters that people suggested here, its kind of better but again its anoying, maybe problem is with Glass screen protection.

Im from Serbia, mobile carrier is MTS, Build number V3.05