Iphone 3G wont backup after installing IOS4. Unknown error code

[superdm1]

After installing IOS4, i tried to backup but got an error occured when trying to restore iphone (-402653077).
Iphone is now stuck with apple logo when i turn it on, or just does same error when i connect to itunes.
Apple online support has no answer that helps, any suggestion would be appreciated.

 

[superdm1]

update

after restarting iphone a few times, it now gets a lil further along in the restorstion process but then stops saying cannot find correct disk. After it shows apple logo again then does same thing again