Why can't MS create a new browser from scratch based purely on .Net? The current browser is enough of an embarrassment that it would serve them well to release something new that is:
As standards compliant as possible (yes, even pass the stupid Acid tests 100%)
Secure. Using .Net will give them a lot of security out of the box. There is your sandbox right there. You need to try really hard to create an insecure app with .Net
Have a good plug-in API. Using .Net will allow much easier plugin development, including being able to force plugins to be secure. No untrusted code. No memory leaks from badly written plugins. No invalid memory access, corrupted memory,
*Note, I say "fast", because even though .Net apps will always be slightly slower than native apps, the overhead is not that much, and currently IE is roughly 20 times slower than the competition in some places, so creating something newer that is faster
than what we have now should be possible with a well designed, well implemented .Net version.
And don't tell me they can't afford it. Yes, this would be a monumental task, but IE is one of MS' apps that are quite visible to the public , the press and end users. It is hurting their image. Putting resources into developing a better IE should be a high
priority I believe.