Not Found errors on everything

OK, NONE of the internal links on my blog work: Comments, Categories, etc. Just loaded this a week or two ago (latest version) and thought it was all ok. Everything is in my www. directory, as below. Also, and this is probably a great clue: I can create/save pages, and in Manage/Pages I can EDIT them, but CANNOT VIEW. WP can’t find where it’s just created something? (the ViewSite function works though…) I’m a newbie, and am SO confused. Please help.

(I may need to add the www and/or full url, but how?). From the main blog page (www.marthamcginnis.com/blog), if I try to “comment” on the first article, I get the “not found page”: This is what’s in the browser address line: “http://marthamcginnis.com/blog/2006/05/23/is-your-meeting-sticky/#respond”
and this is the error message at the same time:
>>>>
Not Found
The requested URL /blog/2006/05/23/is-your-meeting-sticky/ was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Apache/1.3.36 Server at marthamcginnis.com Port 80
>>>>>>

Many THANKS!!! Martha