Can't Get into phone

Hey guys, i am having a problem with my friends android phone.

he is trying to transfer all of his txt messages to my pc for legal reasons, and i know how, but everything you press the power button it says "unfortunately, the process has stopped."

i know how to clear the cache and all that jazz, but it keeps popping up as soon as i press Ok.

i can get the the settings if i move quick enough but from there i cant do anything. trying to avoid a hard reset as the messages will help my friend get full custody of his child.

thanks in advance,