30 seconds is the maximum time the shutter can remain open in any setting, other than time exposures. If you have actuated the shutter with the lens cap on, it may start attempting an exposure at 30 seconds. If this is the case, just turn the camera off, and try again. If you are in manual mode, you can select a shutter speed anywhere between 1/4000 of a second (very fast) and 30 seconds (as slow as it goes, needing a tripod). If this is the case, then use the camera's shutter speed adjustment to set a different shutter speed.
I'm not aware of another 30 second clock, but if you can explain further what you are doing and when it appears, that might help.
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I'm not aware of another 30 second clock, but if you can explain further what you are doing and when it appears, that might help.