I am getting following error. I can get into control panel and do all other things, but while posting get this error:

Your referrer check is turned on - if you are behind a firewall it's gonna choke on a post. You need to either add your own site as a trusted site in your firewall or turn off the referrer check

Some security suites and virus scanners can also trigger this error; you can generally disable refer filtering in the utility on your (or your users) machine.

As for disabling the referrer check, whereas I don't recommend it, can solve the problem; however, if you find yourself with excess spam messages it's possible it's from this being disabled.

it seems related to some cookie issue. since I resolved the login problem I mentioned in other thread, I have not faced this problem again

It's kind of odd that photopost's php prefix was causing the referrer error... As the referrer error doesn't really do anything with PP... But hey, it works now at least ;)...