Macbook pro shutsdowns all application and logs-out when it goes to sleep

My laptop logs me out and shutdown all application and goes to the login screen. This happens everytime it goes to sleep. This morning it happaend when i loged in and it loged me out and took me back to the login screen. Any idea why its doing this ?

Model Name: MacBook Pro

Model Identifier: MacBookPro6,2

Processor Name: Intel Core i5

Processor Speed: 2.4 GHz

Number Of Processors: 1

Total Number Of Cores: 2

L2 Cache (per core): 256 KB

L3 Cache: 3 MB

Memory: 8 GB

Processor Interconnect Speed: 4.8 GT/s

Boot ROM Version: MBP61.0057.B0C

SMC Version (system): 1.58f16

Serial Number (system): 7302800WGPQ

Hardware UUID: 97BF3FA8-E6CB-5572-8DE6-C203348C5C76

Sudden Motion Sensor:

State: Enabled