I think he means the PC in the game, not his PC as in his PC IRL.
The only thing I can think of that'll cause this is bad codes.
If you're using an emulator, load up your game. Go to Cheats>Cheat List>Remove All. Then try your PC.
If it still doesn't work, do the same thing as what I said earlier, but don't look at your PC yet. Save your game using the normal save funtion (press start and save) in Pokemon. Then press CTRL+F1. It'll reload the game. Load your save file as you would normally for a Pokemon game (you know...pressing start/A through all those scenes until you get to the menu, then load), then try your PC.
If it's the real thing, load up your game with the cheat device, but don't turn any codes on. Save and turn the game off. Load it up again without the cheat device at all. Try your PC.
That's all I can think of.