Weird character "ďťž" before page loads. What is this?

[eluser]term25[/eluser]
I have a strange problem with codeigniter.

When I click on a like within a page, for example I want to go from homepage to contact page

so I am here:

Code:

http://example.com/

and go here:

Code:

http://example.com/contact

and between the page is loaded a strange characters

ďťž

appears on a white page.

After a sec or sometimes less my contact page is loaded.

What is this?

What can cause this behvaiour?

Thanks in advacne for any advice how could I fix it.