The reason why you should check your DSLR shutter count. Do you know, DSLRs have their own life time? It is based on how many counts of the shutter releases. When you exceeded the shutter count limit, it is time to change your DSLR with a new one or replace with a new shutter.
Almost current DSLR models put the shutter count information inside the pictures. The information is located in the pictures metadata and can only be viewed by using special software like Opanda IExif .