Object not found

hello – getting a problem with the site i’m building
– i’ve already searched all over the forum and found no answer to help me.
– I’ve deleted and re-created all of my pages & menu – still the same issue
– I did notice that if I save a page as a draft and click preview page – I can see it but once it’s published , I get the error
– i’ve got the permalinks custom structure correct: /%postname%/
-everything works fine on the other site i’m creating
– im using thesis theme and wordpress nav

here’s the error message i got:

Object not found!

The requested URL was not found on this server. The link on the referring page seems to be wrong or outdated. Please inform the author of that page about the error.

If you think this is a server error, please contact the webmaster.

Error 404

THANK YOU THANK YOU THANK YOU for your help!!!!!