I have done a bit of research and discovered that this is Microsofts answer to Adobe Flash.
The question is, it keeps crashing. I click on the button to stop it running can never see any difference on my web pages as a result. So do I need it???
I use Firefox and NOT Internet Explorer.
Personally I won't touch it ...
.. and there aren't that many sites that use it - seems it's going the way of the dinosaur ;) As is, however, Flash.
There are a few video services which still use it - IIRC ITV's online player used to use it (so I had to install it to watch Tour de France highlights!).
For most stuff it isn't necessary. I would remove it and just re-install it if you find it necessary.
Cheers, Mike
Its on its way out.. like Flash...thankfully.
You will probably finds its a lot more stable in internet exploder so maybe the trick is to disable it in firefox ?