Causes of continual preference corruption?

Other considerations to prevent corruptions that I have seen for all computers:

1.  Use a UPS (uninterruptable power supply, approximately $100) that is always on and always cleaning the power that comes in to your computer. (Stand by power supplies may not work as well, read the package.) This can prevent high and low voltage spikes that effects saving data to the computer.

2. Check the computer power supply with a multimeter, or take the computer to a computer store and ask them to check it.  It might need a new power supply.

3. Don't put carpet in your office.  If you ever feel a "shock" then you have this problem, regardless of carpet or not.  Shocks destroy data and also computer components.  Never buy used memory for your computer since it may have been improperly handled and may no longer be good.  To prevent shocks buy an anti-static mat and put it under your chair, wear cotton, do NOT use rubber sole shoes, and connect your mat to a grounded outlet (and test the outlet to make sure it has a good ground by buying a ground tester at Home Depot or Lowes).  If the anti-static mat is not grounded then it does NO good.

4.  Turn off, at minimum, and consider unplugging your computer during a thunder storm.   Power spikes can also come in through your Internet connection. Lightning can do strange things, like jump across space, if it is high enough voltage, and destroy expensive equipment, sometimes even if it has a surge suppressor. 

Again, if you don't have consistent clean power then what you save to your computer may be inaccurately saved.  You will see the result of power problems as your computer slowly degrades and gets more mysterious errors, not just in Captivate.  By then it's probably too late and you should consider buying a new computer (with UPS).

A UPS will not last forever... each time it successfully protects you, then it protects less.  Some devices have a light to show how much they protect - the weaker the light the less protection.  When it goes out then it is not protecting your computer.  Buy a UPS WITH a light.  Do not buy a replacement battery since by that point the rest of the components are probably not providing maximum protection.

Do you run Captivate as Administrator?

Just another thought: are you using a theme packaged with Captivate or custom themes? It happens that the Layouts in the Public documents get corrupted as well, that is the folder with a copy of the packaged themes. Any edit to those themes will be saved in that folder. If you use a custom theme, that is not necessarily the case.

Are you by any chance working on a corporate network and working on CPTX files that are stored on a LAN drive?

Are your Default Locations in Preferences pointing to folders that are on your local PC hard drive?