help error in console??

my mac is acting weird i can't tell why its moving slow over heating and app crash all the time. i keep getting this error message in console and i have no idea what it means

4/18/16 11:23:30.002 PM Dock[304]: com.apple.message.domain: com.apple.dp.failure

com.apple.message.signature: Failed to retrieve the last 10 desktop images.

com.apple.message.signature2: boot

com.apple.message.signature3: 2040

com.apple.message.summarize: YES

SenderMachUUID: EC8A5F54-7CE2-3FC0-AC0D-D0D156C930

i have a macbook pro a1278 2.5 i5 4 gb running el captain 10 14 4