I'm unfamiliar with this "optimized" IE8. Is MSN your isp? This sounds like the MSN Explorer that MSN provides along with their software. In any case, since your QVC problem began after installing the optimized version, it seems likely it has some settings preconfigured that QVC is having issues with.
You might try resetting IE to default settings, although that may remove the "optimization". Have a look here and you can either use the Fixit (easier), or do it manually. How to reset Internet Explorer settings
You may find it easier to install Opera (my preference) or Chrome, or Firefox, and use that for QVC only