Help identifying this browser (User Agent)?

I’ve had a couple people hit my "click here if you are using a mobile device and were not redirected" page. It displays to them the User Agent string of their browser and also sends me an email with the info.

I’ve gotten this User Agent a couple of times, but I don’t know what browser (or crawler) it is from:

Browser: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.0.3705; .NET CLR 1.1.4322)

Anyone know?