CKFinder integration popup fails on second load

Very quirky functionality and I'm stumped as to why this occurs. When I first log into my site's admin and attempt to load images for the first time (CKFinder 2.2), the image/link options work fine. However, when I try to do it again to add/edit content, I get a 404 on the CKFinder window launch.

My folder structure is:
/admin/
/admin/fckeditor/
/admin/ckfinder/

However, this is the 404 error I get

HTTP Error 404.0 - Not Found
Requested URL http://foobar.com/admin/fckeditor/edito ... inder.html
Physical Path e:\web\foobar.com\admin\fckeditor\editor\ckfinder\ckfinder.html

In fckconfig.js, I connect to CKFinder like so:

FCKConfig.LinkBrowser = true ;
FCKConfig.LinkBrowserURL = '../ckfinder/ckfinder.html'
FCKConfig.ImageBrowser = true ;
FCKConfig.ImageBrowserURL = '../ckfinder/ckfinder.html?type=Images' ;