yet another IE display problem

I know this is a common issue and usually I can find a work around. However in this situation, the error occured spontaneously and in fact, it still displays properly in IE but just as a flash, which then disappears. It worked well in IE up until last night when I changed the add to cart button and removed the text 'Product image' from the index.php english file.

This link is an excellent example. The box at the top displays properly, using essentially the same styling as the product listings. In IE the product backgrounds and borders now dissappear.
Using IE 8.
Please advise

Might start with with the HTML error - http://validator.w3.org/check?verbose=1&uri=http%3A%2F%2Fwww.secondnatureaquariums.com.au%2Flivestock%2Findex.php%3Fmain_page%3Dindex%26cPath%3D3_13

ok thanks working on those. They would have been like that yesterday though when all was functioning

html errors and warnings fixed. Same issue remains. Is it a CSS thing? btw I use that CJ loader thing, so I have found that sometimes I have to repeat CSS bits onto the end of some other .css files.