how to stop 'Unknown' appearing when calling

[Guest D-boyy]

Hey all, noob here but I did search for this problem before posting so go easy.

Basically whenver im in a call (whether dialling or recievieng) I get 'unknown' written at the top just above the contact image covering some other writing...

Anyone know what I can do to get rid of it?

I'm running FLB r10 and have the Galaxy S theme