although, coincidentally, i was planning on starting a new file on my copy of sapphire, when i turned it on, it said the save file had been deleted. why is that? what could i have done that caused that?
Check out this message on the Ruby board: http://boards.gamefaqs.com/gfaqs/genmessage.php?board=471243&topic=43105436
Most likely your game is a counterfeit. I picked up a copy of Ruby from eBay and had the same problem. Every time I tried to connect to it (even if just playing Diamond on the DS while Ruby was plugged in the GBA slot), it would erase the save file.
There's a couple things to check. The cartridge color should be a slightly translucent blue. And then try looking "up inside" the cartridge (where the metal connectors are). Right above the line of metal connectors you should see printed on the circuit board "(C) 2002 Nintendo" or something like that. The bootleg copy I had didn't have this. Also, when "looking up inside" the cartridge like that, I could see there had been some plastic on the divider there cut away.
I suppose there could be other reasons for the save file to get deleted... but this is what happened to me w/ my Ruby copy. I immediately returned it, went to Gamestop and bought a copy and tested it right there... got a legit copy.
i got lucky, i just beat the elite four and i had traded all my pokemon onto firered so i could start a new file on sapphire. and the time that I turned it on, it had already been erased. i wonder what made the game last over 75 hours and then get deleted.