This site has an inconpatibility with ie6…R6025 pure virtual function call when trying to log in. Microsoft offer a hot patch fix and to fix it properly in a future general patch.
Oliver Townshend says: (this is the best explanation)
which means that wordpress called a virtual function on an object at a level where there’s wasn’t actually any function to use (probaby the function at the bottom of the object heirarchy).
LOL, They fixed the computer today. It took 111 patches and about 3 hours.