Same/similar problem arose today. Here’s the behavior in Firefox 2.0.0.11 (Under Vista, which BTW installed many OS updates just this morning):
[myblog]/wp-admin/index.php begins to show, then goes blank. It does not say “done.” Rather, the tab shows “Loading” and does so forever.
I Googled for help, and saw the suggestion to rename my plugins folder, and did so. No change. I renamed plugins back to “plugins” and activated Akismet and Spam Karma 2, which I pretty much can’t live without. Again no change.
Every admin page other than the dashboard comes up just fine.
The behavior is the same in Opera 9.24.
The dashboard comes up in EI7.06. When I capture the source from that page and save it locally, FF and Opera open that local page with no problem. Cannot capture source in either FF or Opera.
I did not try Opera or IE7 before I put the plugins folder back in place and reactivated Akismet and Spam Karma 2.
BTW, I discovered the problem by trying to post to my blog using Live Writer 2008. It couldn’t log in to the blog to post. It still can’t.