Please Help. What is roi.ltcdn.com? How do I correct it?

I belong to a website called Roiworld. roi.ltcdn.com came up and I cant get into a lot of pages without a small dialog box asking for my pword and user name. I type them in correctly over and over and it doesn't take it. Please help me, this is important. I am now leary that it may be spyware. Thank you so much.