pushState causing postback in IE 7 >

Currently I'm doing a server side redirect which appends the location hash like so...

SearchTerms[]=web&PageNo=1&开发者_开发问答;PageSize=10&Sort=0&AllFacetGroups=null

When I call pushState to update the location hash, this fires a post back.

Note this does not occur in FF but in IE (7 and above) for some strange reason it triggers a post back.

How can I stop the post back from happening?

---

Ok the hack to get round this in IE is to redirect using the document.location.href, this correctly initializes the location hash. Redirecting using the server fails to initialize the document.location.hash.