i am unable to open Houdini help from help menu, once i clicked Houdini help from help menu, the safari browser pops up and says that safari can't open local host? what is the problem?

Maybe you've got a firewall blocking the self-hosted web services Houdini needs to display the help system.

You can also browse the help folder contents directly, but some links won't work correctly.

/Library/Frameworks/Houdini.framework/Versions/12.1.230/Resources/houdini/help/_index.html

i dont have a firewall

What operating system? As far as I recall, all OSes which Houdini run on come with system firewalls these days.

Mac lion, I checked th firewall option in System preference, it is turned off. Is there anthoer firewall?