In addition to not being able to plant berries, play the lottery, and Espeon and Umbreon, you can't get the Shell Bell, and people who are suppose to give you things daily won't anymore (i.e. the berry master).
Now that I mentioned it, depending on whether Shoal Cave is stuck in high tide or low tide, Snorunt may not be obtainable. It's been a while since I played to but I think that's how it goes.
I've heard that one way to fix the problem is to mix records with either Emerald. I think that works because I have over 100 hours on my Sapphire and it hasn't frozen. A certain other website details... see the link in Ruko's post.