Do as ColinL says, find where the hole is first. Then post what you find here and someone will probably be able to diagnose it.

There are a lot of things that could be causing the flats and the info will help.

As an example: I had a rough spot on my rim at the valve stem and kept getting holes rubbed in the inner tube at the base of the presta valve. After a few flats I noticed, filed down the burrs and never had that problem again...