Reading the manual in a quiet room with a pint of beer and no other distractions usually helps.

Try this though taken from another site re E420

"One last thing to try, a reset of all settings to factory default. First turn off the camera and remove the lens. Then put the lens back on. This ensures that the electrical contacts are all seated properly. Then turn the camera on and follow the instructions on how to do a factory reset that are on the top of P. 30 of the instruction manual. After you do that, you'll have to go back through the menu system to reset any of your previous settings that you wish to continue to use. In particular, be sure and set Live View AF mode to AF sensors per the instructions on P. 37

No, it doesn't matter what shooting mode you're in. If you've gone through all the settings I've recommended and the procedures above and you cannot get your camera to do an exposure lock, it is malfunctioning. If you just purchased it, I'd suggest exchanging it for a new one with whoever you bought it from. If that is not feasible, Olympus will fix it for free if you send it to the service center whose address is on the warranty card with a description of the problem. Call them before sending in the camera and talk to a service representative for the E-520 who may have some diagnostics for you to run through before sending the camera in. Also, be sure and ask him what you should do to prep the camera for shipment (basically take all removeable items off of it including lens, battery, CF card, hot shoe cover etc.)"

EB