Last night, I got around to investigating the new Web Slice functionality in IE8. I browsed to http://uk.msn.com/ and found various slices in the home page. I installed the 'News' slice and then clicked on the button in my Favourites Bar...to be greeted by a rude message saying that "Internet Explorer cannot display the web page".
Bemused, I went binging and soon discovered that Google Gears and Web Slices don't play nicely together. Unfortunately, this wasn't the answer. I don't have Google Gears installed. However, this prompted me to start working through my various Add-ins, disabling them and restarting the browser. Eventually I found the culprit. Web Slices, it appears, don't play nicely with Microsoft's 'Windows Live Family Safety Browser Helper Class' add-in. Why I had this installed and enabled on my work notebook, I cannot say (the kids are not allowed anywhere near my machine). Anyway, disabling the add-in enabled the new Web Slice features in IE8.
I couldn't find any mention of this anywhere on the web (not even when I googled rather than binged). Maybe the problem is specific to my machine. Before anyone asks, yes, this is repeatable. Every time I switch the Family Safety add-in back on, web slices stop working. Maybe web slices are deemed to be dangerous and this is by design. Anyway, I hope this post will save someone a few minutes of annoyance. I am, incidentally, using IE8 RTM on Vista Business with SP2.