Hi Joe, I'm writing this up just in case it is a fixable bug, and for essential catharsis if it is not.
I upgraded a site from 2.3.9.0 to 2.4.0.2 today, and the menu broke in IE and FF. It was a standard horizontal portal:SiteMenu. Also, various other things were not working, like a RSS scroller. Everything worked fine in Chrome.
After much investigation, the cause turned out to be this CSS in style.css:
#ctl00_mainContent_OrderDetailView1_lblTicketPrice:after { content:' (not really! The actual amount will be on your invoice) '; }
It appears the mojoPortal CSS combiner breaks this across lines on the final bracket, which in IE/FF causes problems.
Changing this to
#ctl00_mainContent_OrderDetailView1_lblTicketPrice:after { content:' not really! The actual amount will be on your invoice '; }
makes everything work again.
Could the css combiner avoid breaking lines on the bracket?