APM document content changed

Hi, 11.5.4 HF2 Standard HTTPs VIP (ssl bridge) with APM auth (not portal auth, just auth against AD, NTLMv1 SSO and then goes to def. pool)

 

Browsing is OK, but when I click to some document, I get it, but it has name my.policy and its content looks like this:

 

 

It appears only in IE, in FF it works fine. Anyway this is very strange, do you have any tips or so what to check? I did not disable any javascripts or so, just ordinary browser settings

 

Thanks, Zdenek