Power Windows

I have a 2001 hyundai elantra. The power windows seem to not work once in a while. I guess it started a few months back when my passengers can't open their windows, I have to do it for them. Now the windows only operate once in a while. It almost seems related to the hot weather. It will work early in the morning and then not in the afternoon. What can I do to fix this? (Hopefully it's not too expensive! Heh heh.)

Thanks.

Check all your relays and fuses. Make sure none of the fuses are blown and make sure the contacts on the relays are clear of debris or corossion. Just a place to start.