I may have discovered a bug in internet explorer 8 but can’t find a way to report it to Microsoft.
Firefox renders some things quite differently to Internet Explorer.
So to test the appearance I keep changing my default browser between the two.
On Windows 7 Pro 32 bit;
When setting Internet Explorer 8 as the default browser it does not overwrite the registry settings in HKEY_CLASSES_ROOT\http\shell\open\command as well as several other nearby registry locations.
This means that Firefox remains my default browser regardless even though Explorer thinks that it is the default browser.
When I click 'Make IE8 the default' it clearly makes a change somewhere as it then thinks it is the default even though it isn't.
It is possible that there is another explanation, but it really does appear like a basic bug.