Flaw in WordPress theme means more work

Something that I find frustrating about my chosen work is that I sometimes feel like I am taking ten steps back for every step I take forward. I found out the other day that the theme I had been using on many of my WordPress blogs was not showing up right in Internet Explorer. It looked right in Firefox, but when I opened one of my sites in Internet Explorer it was all messed up. So... back to the drawing board on all the sites I had carefully created using the flawed theme. grrrrr