Dell Inspiron 1545 Goes into Sleep mode randomly

Hello Everyone, I have a customer who has a Dell Inspiron 1545, and it goes to sleep randomly.

Here is what it is doing:

• When typing a document in Microsoft Office, Word Document, and even Notepad the computer will power down into sleep mode
  
  • It won't lose it's data, but it won't let you boot up for a little bit either.
  • It will boot back to a login screen then your right where you left off
  • Doesn't take a long time for it to happen either
• While hosting a presentation user was able to stay on for 1.5 hours with no trouble, much longer than typing a word document would have allowed
• Computer will cut off on battery, or while plugged in

I'm not sure what's causing the issue, but here is what I have done

• Taken the laptop apart, and blown it clear of all dust (very little in there)
• Ran Disk Cleanup (Despite thinking it's hardware related)
• Checked that the Power plan was optimal
• Scanned for Viruses

Anyone have suggestions?

Thanks