I am a newbie, so forgive me if I don't use all the right terminology.
I have just upgraded to 1.5, and it's great (thank Goodness--now you can edit users!!!)
However, I am experiencing a glitch: when you post or comment and then click on "view site" (RIGHT above the editing box, NOT at the very top of page), you get an error message "_default_ could not be found. Please try again."
And after you post a comment, to make matters worse, you're trapped in the comment page forever, because there isn't even a view site link, and clicking the title of the blog (in the banner) gives the same _default_ error message above. You have to type in the URL again to view the site after writing a comment!
So the link to the main site is incorrect. But is it an error in the 1.5 template, or is it an error in my site? And how do I fix it? I had some luck in the old 1.2 with editing my own template to add various features, but I can't see this template (used to be accessed by clicking "template" in admin on 1.2). Yes, I see Manage-->Files-->Main Template (but that template is 4 lines long! The one on 1.2 was the whole page, so it was easy to tweak.)
Thanks again, and again, please forgive my ignorance. I am learning more about WP every day.