Mangled Portal UI (when accessed using nlb name)

Hi, my FIM portal is installed on 2 servers for Load Balancing (Windows 2012, SharePoint Foundation 2013).

When I'm accessing it by using name defined for NLB (using hardware LB) UI sometimes (approximately 50%) shows in corrupted way - similar as it was with problem: http://social.technet.microsoft.com/Forums/en-US/2165289c-e91b-477b-a1c3-f30da9467d8a/mangled-portal-ui?forum=ilm2

When I'm accessing it by using name of first or second server it always shows correctly.

It is not redirection issue this time (but I think something similar).

Any idea?