Hey, but one of you found a gold charm
Sorry to tell you, but I knew what I was looking for and where to find it - there was nothing random about it at all. And nothing out of the ordinary performance-wise occurred with my detector, either.
Metal detectors work in a relatively low part of the frequency spectrum, when compared to the emissions from solar flares and other atmospheric, electromagnetic phenomenon. Solar flares, in and of themselves, have a goodly amount of EM power upon reaching Earth, enough to ionize the upper reaches of the atmosphere. Yet at the surface, their RF effect is downright miniscule, on the order of micro-, even nano-, watts... thanks to that very same atmosphere.
There has to be far more transient power in any contaminating signal than that, in order to affect a detector. That's why things like power line emissions and AC motors at start up are cross coupled into a detector's antenna (coil) - lots of power, just 'abursting onto the local scene with RF energy. Fortunately, RF energy degrades quickly the further you get from the source and you must be close to that emission source for this coupling to occur.
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The solar flare that could pack enough whollop to seriously degrade a detector's performance would make little difference to you, anyway. You'd be too busy with other things to be out detecting. Things like dodging gamma radiation and trying not to get microwaved with all the other life on earth, come immediately to mind.
Phases of the moon, the number of times a cricket chirps at night or weather predictions from the Farmers Almanac are equally ineffective when it comes to upsetting detectors. No offense, but perhaps you should quit watching the "Psychic Friends" network; and stay away from the Drudge Report, Rolling Stone magazine and The National Enquirer, while youre at it.