Dueling Browsers…

I’m sure this is as obvious as the nose on my face, but I can’t figure out what’s wrong:

After what I thought was a successful tweak of the MistyLook theme on my LocalNetwork sandbox (I checked it on Firefox and everything was where it was supposed to be) I tried it on the Internet Explorer browser – and it wouldn’t format right.

On the home page the sidebar completely vanished, and only the first two posts are visible (and I can’t scroll down to reach any of the other posts, or see the footer).

Also, the background color in the contents area isn’t showing: it defaulted to plain white. The other linked pages seem OK – the footer’s are there – but so is the default white color).

Although I did make a lot of changes to the theme (I moved the “header” up and the “navigation bar” down, and slightly altered the sequence of the sidebar boxes, and added a single.php so I could alter the single post page) the changes are working OK in Firefox.

So, why is Firefox being a good boy, but Explorer such a juvenile deliquent?

Did I inadvertently clip out some code necessary for Explorer to do what it’s supposed to do that doesn’t affect Firefox? If so, can anyone tell me what code to look for to remedy the problem?