Yes, - that's because the homepage clients link is to clients.html, and the services page clients link is to Clients.html.
Browsers when viewing pages 'live' can be fussy about case sensitivity and won't allow wrongly cased links to show, while viewing on your home machine you can often browse the site without any problem.
You may just need to change the clients and services pages links to 'clients' to (lowercase) clients.html.
It is certainly worth getting rid of the duplicate .css & .js paths in the head area though.
Yes - cool design. I like sharp clean layouts!