joomla menu not visible

I am facing somewhat peculiar problem. i have two systems, both running xampp 1.7.1 . our site is based on joomla 1.5.10. One system is using fedora 12, the other one is using rhel 5. The problem is, in rhel system we can create delete and rename menu items. But this changes are not visible on the frontend. I mean, if you login as an administrator in admin panel, you can view the menu structure, and changes are visible there. But in the front site, menu change is no开发者_StackOverflowt visible. This problem is not occurring in fedora 12 system running same xampp version. There all menu changes are visible normally. I have used Swfreemenu module 5.2. One more thing i observed,if menu is renamed, in the menu table the change should be saved along with a checkout time. In fedora this is happening. Nut in redhat, all other columns are saved except the checkout time(timestamp). That field is filled with "00000".

Do you have caching turned on?

If that's not it then I always do the print_r to get the query and results and see where/why it's getting.