I found this on a thread in DPR's Sony SLR Forum.
A forum member had a problem with her A300, that just displayed half a picture. It looked like the shutter was broken.
She received help from Sony and they gave her some instructions that seem to have solved her problem.
Im posting the instructions here in case someone who reads this blog ever has a problem with a Sony Alpha DSLR and this may help.
1.- Turn camera OFF
2.- Take out memory card
3.- Take out battery
4.- Turn camera ON for 30 seconds and then turn OFF
5.- Put battery back in
6.- Turn camera ON and go through the menu until you find the option RESET DEFAULT
Hopefully this will work when you dont know what to do.
Another solution I know from personal experience that applies to most electronical devices when they start acting weird is:
1.- Turn device OFF
2.- Remove battery or unplug power cord or disconnect battery (in case you cant remove it)
3.- Wait from 20 to 30 seconds
4.- Put battery back in, plug power cord or reconnect battery
5.- Turn device ON and check if that solved the problem
This usually solves most problems related to weird operation AS LONG AS THE EQUIPMENT ISNT PHYSICALLY DAMAGED OR HASNT BEEN TAMPERED OR INTERVENED.
If the problem you're having persists, you need to contact customer support. On the link list to the right youll find the eSupport site from Sony that will redirect you to the proper site depending on your location.
Source For System Reset