UPS
http://www.amazon.com/CyberPower-CP1500PFCLCD-Compatible-1500VA-Tower/dp/B00429N 19W/
Mac OS X Forum
https://discussions.apple.com/community/mac_os?view=discussions
Recovery Mode
http://support.apple.com/kb/HT4718
TimeMachine 101
https://support.apple.com/kb/HT1427
http://www.apple.com/support/timemachine
General purpose Mac troubleshooting guide:
Mac OS X: Starting up in Safe Mode - http://docs.info.apple.com/article.html?artnum=107393
What is Safe Boot, Safe Mode? (Mac OS X) - http://support.apple.com/kb/HT1564
Isolating issues in Mac OS X
Creating a temporary user to isolate user-specific problems:
Isolating an issue by using another user account
Identifying resource hogs and other tips:
Using Activity Monitor to read System Memory and determine how much RAM is being used
Starting the computer in "safe mode":
Mac OS X: What is Safe Boot, Safe Mode?
To identify potential hardware problems:
Apple Hardware Test
General Mac maintenance:
Tips to keep your Mac in top form
You should have TimeMachine saving your work, YOU need to be doing Save As somewhere else as you work, you don't say what application and whether you have Lion 10.7 or later (10.8.4)
Can't say enough for the importance of using a UPS. Get one and plug your modem, router, computer into one and don't worry about data loss and lost modem or corruption or the effects to electronic devices.
This forum deals with a desktop/tower 65lb Mac Pro
http://www.apple.com/support/macpro