Wouldnt happen to be an iPhone by chance , would it ? My guess is that an application is interfering with some of the functions on your phone . If your using it for business and your company had new software , or switching over to a new system …..BINGO ! there is your problem . Either way , do yourself a favor , and make a hard copy of your address book numbers . The company I work for is switching over to a new system …….its not on line yet , but its already creating problems with some of the basic , and unrelated functions of the iPhone . Also , Apple has put out some bad updates now and again . They always correct it ……………..but that doesnt help the poor bastard that has to deal with it until they do .