My macbook keeps randomly turning off.

Question

My macbook keeps randomly shutting off. It is no longer under warranty. I've read all of these discussions from people with similar issues and I've tried some of the things that seemed logical. it's a late 2007 MacBook. I bought it used from a friend and they never had this issue. It was wiped clean and when I got it, after about 5 LONG uses, it randomly shut down once. I installed Snow Leopard, updated to 10.6.8, then the problem started. The fan seems to be running fine. The problem occurs weather it's plugged in or not, so I'm pretty positive it's not the battery. I've done the PRAM reset and the SMC reset.. I also took the computer apart and cleaned it. Performed the SMC reset again and it seems to be working for right now. Hopefully that's all it needed but if the problem continues does anyone have any suggestions on what it may be? Thanks.
Extra Info:
Model Name:          MacBook
  Model Identifier:          MacBook4,1
  Processor Name:          Intel Core 2 Duo
  Processor Speed:          2.4 GHz
  Number Of Processors:          1
  Total Number Of Cores:          2
  L2 Cache:          3 MB
  Memory:          4 GB
  Bus Speed:          800 MHz
  Boot ROM Version:          MB41.00C1.B00
  SMC Version (system):          1.31f1
  Serial Number (system):
  Hardware UUID:
  Sudden Motion Sensor:
  State:          Enabled
Battery Information:
  Model Information:
  Manufacturer:          DP
  Device name:          ASMB016
  Pack Lot Code:          0002
  PCB Lot Code:          0000
  Firmware Version:          0110
  Hardware Revision:          0500
  Cell Revision:          0102
  Charge Information:
  Charge remaining (mAh):          4859
  Fully charged:          No
  Charging:          Yes
  Full charge capacity (mAh):          4859
  Health Information:
  Cycle count:          247
  Condition:          Normal
  Battery Installed:          Yes
  Amperage (mA):          275
  Voltage (mV):          12598
System Power Settings:
  AC Power:
  System Sleep Timer (Minutes):          10
  Disk Sleep Timer (Minutes):          10
  Display Sleep Timer (Minutes):          10
  Automatic Restart On Power Loss:          No
  Wake On AC Change:          No
  Wake On Clamshell Open:          Yes
  Wake On LAN:          No
  Current Power Source:          Yes
  Display Sleep Uses Dim:          Yes
  Battery Power:
  System Sleep Timer (Minutes):          15
  Disk Sleep Timer (Minutes):          10
  Display Sleep Timer (Minutes):          15
  Wake On AC Change:          No
  Wake On Clamshell Open:          Yes
  Display Sleep Uses Dim:          Yes
  Reduce Brightness:          Yes
Hardware Configuration:
  UPS Installed:          No
AC Charger Information:
  Connected:          Yes
  ID:          0x0100
  Wattage (W):          85
  Revision:          0x0000
  Family:          0x00ba
  Serial Number:          0x00a0caf9
  Charging:          Yes

Answer 1

Resetting the SMC of an Intel-based portable Mac with a battery you should not remove on your own
Note: This will not delete any data.
The SMC is responsible for controlling various system functions. None of your data will be deleted by resetting the SMC.
Shut down the computer by going to Apple () > Shut Down…
Select Shut Down or allow the computer to shut down automatically.
Plug in the MagSafe power adapter into a power source and then connect it to your Mac if you have not already done so.
On the built-in keyboard, press the (left side) Shift (⇧), Control (⌃), and Option (⌥) keys and the Power Button at the same time.
Release the (left side) Shift (⇧), Control (⌃), and Option (⌥) keys and the Power Button at the same time.
I hope I answered your question.
Austin