Why is my IE 11 reporting a bad UserAgent String??

My IE 11 on W7 Ultimate is reporting the following UAString

Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/7.0; SLCC2;
.NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; .NET4.0C; Media
Center PC 6.0; .NET4.0E; InfoPath.3)

This is causing problems with some websites - Adobe thinks I have IE8 installed :( as doeshttp://whatbrowser.org/

How can I rectify this (where is the "reset my UA to default option???")

Thanks!