In a situation like this, you can't really overlook the fact that NOTHING should be between a <tr> tag and the subsequent <td> (or <th>) tag; this is the way the w3c HTML standard works. Netscape, by not rendering anything that you put here, is following the standards, whereas IE is trying to show you something for your trouble, even if it ends up teaching poor coding practices.

All that to say that I don't know why a panel  renders as different elements in the two browsers... but you shouldn't be surprised at all if it doesn't show up correctly when you code it that way.