You can save yourself countless agony, loss and time (time is money) by backing up your system volume at key times. So may times we get a phone call and the quote is basically the same, 'my computer was working fine and now xyz is happening.' Then we spend 15-20mins going threw what the caller had been doing in the weeks, days, hours before xyz started happening, almost every time it is due to an update or new software.
The basic rule that we use is before any update, upgrade, new program installation or anything that might change the current setup of the system. NOW DON'T STOP READING. How you back up can be just as important as when you back up. Apple's Time Machine is a great consumer tool for backing up but professionals be warned. With Time Machine if you do something to your system that 'corrupts' it Time Machine will back it up AUTOMATICALLY as well. This makes getting your system easily back to it's previously peachy state difficult.
So what do you do, CLONE! We prefer Carbon Copy Cloner, Do it manually, NOT AUTOMATICALLY for the reasons above. You want a complete bootable exact copy of your disk that was made when everything was working hunky dory. So if you clone you disk when its working well, right before you update, upgrade, install a new program or do anything that might change the current setup of the system and something goes wrong or doesn't work right (which happens often). Then all you have to do is clone the back up back to your system drive and reboot and your good to go. Also once you are confident that the change to your system is stable back it up again.