First thing to do is get rid of the test strips (they just won't give you the accuracy you need to maintain your pool) and get a drop based test kit that will test for:
Free Chlorine
Total Chlorine
pH
Total Alkalinity
Calcium Hardness
Cyanuric Acid (Stablilzer or Conditioner)
There are kits available from Taylor and LaMotte that will do nicely.
The best bang for your buck will be the test kit sold on the Poolsolutions website!
http://www.poolsolutions.com/cart/ps234.php
Once you get an ACCURATE set of test results post them on here with your pool size in gallons and the finish (I know you said fiberglass) and you will get all the help you need with your pool!

Very high levels of chlorine can sometimes bleach out some chlorine tests (depends on the reagent used) I know this can happen with DPD reagent tests, I don't know if the syringaldazine reagent usually used in the test strips is prone to this, if it is it is one possible explanation of your not registering free chlorine. A DPD-FAS titraton test such as in the Taylor K-2006 or the kit sold by Poolsolutions will allow you to accurately test if the chlorine leves are very high.
I notice you mentioned the frog. Is that a PoolFrog? That is an ionizer system that uses (if my memory is right) silver and zinc ions and requires a .5 ppm FC residual. There has been some discussion on this board about them and the general consensus seemed to be to just take them out of the system and use the 3 B's --Bleach, Borax, and Baking Soda. That is what the majority of people on here seem to do and they have very few pool problems (and $ave a lot of money in the proce$$!)_