You are correct that the postback for individual blogs are working correctly.
However, the postback url for the user's main blog itself is not working and sending you to site.com/blogs.php
Here is how I am arriving at the issue:
My blog page at the demo site is: http://demozzz.com/dolphin7b/blogs/posts/mk11232 I have 3 test post there
1. Now I click on RSS Subscribe from my blog main page of demozzz
2. I am given this link to subscribe: http://demozzz.com/dolphin7b/rss_factory.php?action=blogs&pid=99 (click on the link to test to see that it takes you to the proper RSS feed)
3. I subscribe via firefox (name it Demozzz mk11232 blog) and my 3 blog entries showup as those are what I have (picture)
4. Now I don't want to click on an individual entry but go to the blog's homepage to see all entries at once so I click on Open Demozzz mk11232 Blog to go to the main blog page and it is clicking on that link that takes me to http://demozzz.com/dolphin7b/blogs.php
5. Firefox RSS may be the issue? So I test it on my site, I put the blog RSS feed in a RSS feeder on my site to see what dolphin does, well it looks nice and shows everything:
6. However, when I hover over the Blogs RSS feed to go to the main blog RSS look at the url that shows in my browser:
So the postback url for the main blog feed itself is incorrect and will bring you to a page that states Profile Cannot be Displayed for Viewing.