For some reason, all of a sudden, when I recieve a call from someone who is in my addressbook, the number is all that comes up, the name doesn't.
But when I go into the call log, it shows the person by name and not number.

It's because you have content protection enabled or compression enabled most likley.

true..i have solved it by disabling the two options.

if you have a bes sever with a policy, you should unflag the relevant option in the security group