I think the best option is a factory reset. It's kind of a pain, but that is most likely to solve the problem. Before you go that route, remove all the widgets you can; sometimes widgets can cause problems. Just make sure to back up everything, then go into "settings" and find "factory data reset" (I think that is is under "privacy settings" in 2.2). This will revert the device to the way it shipped from the factory. Your wife will have to go through set-up again and reinstall all the apps from Google Play. If that doesn't do it, I would start looking for a new phone.
Answer
I think the best option is a factory reset. It's kind of a pain, but that is most likely to solve the problem. Before you go that route, remove all the widgets you can; sometimes widgets can cause problems. Just make sure to back up everything, then go into "settings" and find "factory data reset" (I think that is is under "privacy settings" in 2.2). This will revert the device to the way it shipped from the factory. Your wife will have to go through set-up again and reinstall all the apps from Google Play. If that doesn't do it, I would start looking for a new phone.