nvm… just started working on its own
I had this happen to me as well. I normally type my entries in Macromedia Dreamweaver so I can get HTML and formatting to look the way I want then I just copy and paste the code into WP. Then the other night I tried to make a post and it just kept dumping me.
I made a test post which worked just fine. I started to just copy the first paragraph of my entry and it dumped me again. It turns out for some reason WP really did not like one of the sentences in a quote that I had. I removed the sentence and the entire entry saved just fine.
That fixed the categories but not the tags.