MacBook Shuts off at Random Times

I am running a Late 2008 Aluminum Unibody Macbook. It always shuts down at random times, even when the battery is fully charged. I have reset my SMC and repaired my disk in Disk Utility, but the problem is still there.

Battery Information:

Model Information:
Serial Number: 6N852045G2VKA
Manufacturer: SMP
Device name: bq20z951
Pack Lot Code: 0000
PCB Lot Code: 0000
Firmware Version: 002a
Hardware Revision: 000a
Cell Revision: 0100
Charge Information:
Charge remaining (mAh): 2271
Fully charged: Yes
Charging: No
Full charge capacity (mAh): 2271
Health Information:
Cycle count: 270
Condition: Check Battery
Battery Installed: Yes
Amperage (mA): 191
Voltage (mV): 12614

Any fixes??

Thanks!