Dreamweaver wont recognize home/index page...

Help,
Can anyone tell me why Dreamweaver keeps telling me that my home page isn't in the local root folder for my site, but shows up in the site files after it rebuilds the cache?

This is a new problem, it saw all files before with no problem. The index/home page hasn't changed or been renamed. I haven't used Dreamweaver in a few weeks, has something got corrupted?

Thanks
Rod