will this problem solved with reinstalling word-press?
If the problem is caused by a core WordPress file, upgrading may resolve the issue. If the problem however has something to do with data in the database, it may not.
Regardless of what you do, be sure to create backups first!
I am actually trying to help someone with a somewhat similar issue. Here was my hail marry pass to them:
I'm just thinking outloud now, things I would test.
The problem is that something as changed, and this changed caused loss of functionality.
Was it a file that changed?
Your WordPress files generally don't change. I'd take a look at the core WordPress files on your account, check the timestamps of when last edited, and see if there is anything interesting there.
Was it a post that somehow caused the issue?
If you know the date the issue began to occur, you may want to delete all posts prior to that to see if that is the problem. I would copy the site to a dev server (or just a separate folder) so you don't mess anything up.
Thanks - but that was the first thing we tried. I've tried it on Chrome & Firefox on Windows 7, and Chrome and Opera on Ubuntu 10.04.
To confirm, did you check for any error_log files in your WordPress directory? Sometimes errors are logged there. Each folder can have an error_log file, so you may need to dig around to find it.