I think the Yellow version is just trying to tell you that it's starting to die. Does it still save and store data? Even when you restart your game, it continues to act abnormal?
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This is a true story...
I pressed the START button and turned off my Blue version game multiple times once while trying to do the "Extended Mew Glitch", and when I turned the game back on, my BLUE VERSION said it was the Poke'mon RED! The colors were all red instead of blue, and instead of Squirtle appearing first on the title screen, it was Charmander. I never owned a Poke'mon Red nor have I ever played one on my Game Boy Advance. I'll tell you this, IT WAS SHOCKING.
The gameplay was no different, though. Everything was normal except for the color, which was red.
I've had my Blue version for about... three--four years and it's never failed on me. The only time the data got erased was when I tried to save some things on my Poke'mon Stadium game. I was just reorganizing the 123 Poke'mon in my PC boxes... (I must have been pretty stupid to do this, despite of what the warning says in the game, after the Title screen). The screen that said "Without turning off the N64, carefully REMOVE the GAME PAK and then place it back into the Transfer Pak," appeared. (Or perhaps--now that I think of it--I read the message wrong... I don't quite remember what the warning actually said when it came up)
Anyways, I did as it told me, the game said it was saving, but then that same warning popped up. My heart started pounding. I turned off the N64 and put the Poke'mon Blue back into my GBA. When I got past the Title screen, it said, "The save file was destroyed!". My heart just sank. All of that effort into getting all of those Poke'mon... it's all just virtual trash now.
But I'm okay now, because I've already got 85 Poke'mon, including all three starter Poke'mon.
[I know a little secret on how to keep your all Poke'mon, even when you restart your game, but I suppose that's not important right now. Plus, you need a Transfer Pak and any of the Poke'mon Stadium (1-2) games.]