Wow, that is strange, and a first for me! lol. have you tried using any other program that has caller id? if not, lets try this, head over to
http://www.ac-s2.com/ and download S2U2, its an iPhone like lock program, but it also has a great caller id with either fullscreen or thumbnail pics, slide to answer, slide to reject and lots more. there's info on his site and over at xda. oh and you can really customize it. but lets start simple. install it and have someone call you and see how it displays.