Doing a fresh install of OS X doesn't automatically wipe the hard drive, but there is an option that will allow you to do so, either with a single pass of zeros or multiple passes of random data (a single pass of zeros will be fine for your purpose). Look for a button that says "Options".

Also, there is no magnet that a typical person has access to that's strong enough to wipe a hard drive, and even if there were you wouldn't want to do that because it would also erase the information about where the individual data tracks are on the physical disk and render the drive unusable.

Given your symptoms I'd also be suspicious of your memory. You should have a Hardware Diagnostics CD that came with your Mac. Boot your system from that disk and run the diagnostics a few times. As long as you're doing all this, I'd also suggest you "zap your PRAM" by booting the system while holding the "command-option-P-R" keys down until you hear the boot chime a second time. Finally, your system may be old enough that it needs a new battery, which you should be able to find by looking at the mother board - it should look like a very short AA battery. They're not real hard to find, but you might have to go to a few places or to a specialty computer store, such as "Batteries Plus" to find one.

HTH - Good luck!


Dana