The previous code computing rowStart will fail when there are theads since tHead...

The previous code computing rowStart will fail when there are theads since tHead contents are also computed inside table.rows.
However, that code probably worked at some time, so perform a computation to ensure that table.rows isn't getting just the tBody contents.
Please cross browser test.
The last code version of this sortables is on http://yoast.com/articles/sortable-table/ and has changed quite a bit. Joost de Valk suggest
using the jQuery based tablesorter.com.