Searched for this bug, but it seems I am the only one getting "thumb\t_img1.jpg" (with a backslash instead of a slash) as the path to the thumbnail when creating a webpage. My settings are as following:

And the result is:
http://www.aspekt1.net/ms/temp/xnview_w ... thumb.html
As you can see the thumbnail is not displayed. Look at the sourcecode: the path to the thumbnail contains a backslash, instead of a slash!
Anyone else?
Martin