Problems with permalinks

Hello, I’ve recently upgraded to WP 1.5.2, and I have a problem with permalinks and contents.

The problem is, when I click the permalink on me blog, it goes nowhere. Same goes with comments. Click on Comments and the blog goes nowhere. It stays at the main page. I can’t view any of the contents in my blog (that is, without going through the admin cp)

I was tweaking my blog just now, and so, I thought it might be a theme-based problem, but apparently not, as I’ve switched themes to check if it’s a problem.

What I’ve done :

• Switch themes
• Turned off all the plugins
• Removed all added stuff around my blog
• re-uploaded the theme I’m using

I’m sure that I did not touch any of the options that I’m already pleased with. My blog was working fine before my tweaking. If it’s my tweak problem, where did I go wrong?

Any solutions?
my blog is here : http://blog.chewxy.com (don’t worry too much about the contents. They’re crappy)