The EzFlash is terrible, take 5 random games. 2 out of 5 games don't work, and 1 of the five games doesn't save.
I suspect the issue might be related to either your MicroSD card speed or your savelist not being up to date as I've yet to find a game that does not run.
Try enabling "Hybrid Mode" in the settings menu (L+R) - this helps with slow MicroSD cards. If you own one of those zany Japanese Kingstons, try a MicroSD speed setting of 3.
In regards to a savelist,
Cory's ezsave list is updated regularly.
QUOTEI don't know why people don't like screws. Clips break - screws don't. I'd much rather the cart was held together by a screw instead of some clips.