I freshly installed WordPress 3.0.1 at http://dokistation.com. I haven't used WordPress in a few years, so perhaps I missed something. But I will explain my problem.
The default "Hello World" WordPress post allowed the use of comments. I deleted the post, and created one of my own. And that's when the trouble began.
The post I created has comments disabled, despite enabling comments and trackbacks on the edit screen several times. Under the Settings > Discussion, I made sure that anyone can post a comment, and that comments are never turned off.
An interesting fact, any Pages created (not Posts) automatically have comments enabled and trackbacks enabled. I disabled them.
It seems that there is something very wrong here. I can't enable comments on my posts for the life of me, and Pages are created with comments automatically enabled.
I have no plugins installed. This is a freshly installed WordPress, with nothing added, no files changed.