There are parameters that you can set, both in the firmware (eeprom in the latest version) and in the host, where you can define the "shape" of your printer. It sounds like you may have mismatched values here. Double check and make sure you have values that make sense, keeping in mind that in most cases, the range of motion is greater than the size of the bed.
What I mean by that is that the bed, which is about 200mm x 200mm, has a homing position that is probably at (-30, -10), and the maximum position of the nozzle might be around (240, 210).