Features of this version are not supported for IE8 like this one:
The new, scrollable tab row is not available in Internet Explorer 8 and lower or in older versions of other browsers. In older browsers, the original tab row will be used.
I extracted this one from the release notes, I would upgrade the browser If it´s making troubles.
I noticed that SR3 i'ts way faster than SR2, I´ve made like 5 installations and no troubles, but I´ll downgrade my IE to see what you mean and help you.