IE is in quirksmode. You might be able to solve the problem by using a strict doctype.
However if that solves it, it is just luck. You have a much bigger structural issue. By using the 20th century technique of using a table to manage layout, you are forced to add an hr tag for each cell. The top portion needs to be a section with each component in divs within the section, and then a single hr could be used in the section.