After months of my cheap Abacus SPOT watch constantly resetting, I found this on the internet:
http://forum.spotstop.com/showthread.php?t=726
I'll reproduce the post here (thanks a million, Kas) in case the page disappears:
“If your watch re-sets when you shake it try this:
1. Open your watch by removing the 4 screws on the back. Then get
a flat object to take off the back cover.
2. Check to see if there is a space between the battery and the battery holder.
3. If there is fold up a piece of tape and put it in the space.
4. Put the cover back on and test it out.
Note: When opening your watch watch the cover as there is a wire attached to it. (Thanks to Icedrey for this)
Be carefully while doing this. I take NO RESPONSIBLY if you damage your watch. It will as void you 90 day warrranty.”
I performed this fix, and I've been running for 4 months without a reset.