compare first and second testcase they differ only by the first table win98 2002121408
*** Bug 241667 has been marked as a duplicate of this bug. ***
*** Bug 221011 has been marked as a duplicate of this bug. ***
My guess would be that there's something wrong with the attribute mapping mess in nsHTMLTableElement.cpp (or nsHTMLTableCellElement.cpp).
Or, rather, the post-resolve callbacks in nsHTMLStyleSheet that depend on them.
the postresolve callbacks will be removed in bug 43178
this had been fixed before by the rules mapping the root cause has been fixed by the checkin for bug 211636 http://hg.mozilla.org/mozilla-central/rev/4738b38a2f3c