I first installed my blog, starting with 2.0.1, over a year ago.
I had two issues that were resolved recently, and I'm documenting them here in case it helps anyone else.
Issue #1: Blank dashboard
Intermittently, I would see no dashboard or only a partial dashboard.
Issue #2: Fatal error when publishing
Whenever I hit publish, I would receive the following error on a new page:
Fatal error: Call to undefined function: xml_parser_create() in [my directory]/public_html/blog/wp-includes/class-IXR.php on line 144
I worked around that problem by removing all URLs from the ping notification section (under Options -> Writing -> Update Services).
Recently both problems were fully resolved (and I finally saw the full Dashboard for the first time) when my hosting ISP added the optional php4-xml library to their php installation.
If you check <?php print_r(get_defined_functions()); ?> (by putting that in a .php file and trying to load it, do a search for XML and see if you see it listed. If not, then you need the optional library installed.
I don't run 2.1x so I don't know if this tip applies to that version or not, but I know it's important for 2.0x.