Page number edit is broken

[Silent1]

The box that shows what page you are on and can be edited to change pages is broken, if you type in a different page all it takes you to is:
http://www.pistonheads.com/gassing/topic.asp?hm=
and if you have someone highlighted for search results (changing the page number used to be the only way to keep their posts highlighted) you get this:
http://www.pistonheads.com/gassing/topic.asp?hm=46...

[Silent1]

It doesn't work on either chromium on debian, iceweasel on debian, chrome on windows or safari on IOS 9.
I'm using the big blue skin.

If i log out on any of the above devices it works.