Here's a
Macrumors Post from last year that looks like it may do what you want...
Hope this helps!
The answer to the original post in that thread is available in Leopard's 'System Preferences' in the 'Security' section where you could enable your Mac to ask for your password after the screen sleeps. This
not after the screen saver has been on which occurs before the screen sleeps.
In Snow Leopard, the preference has been changed to
only after the screen saver has been on. As a result, this causes annoyance since your Mac would ask for your password more often since the screen saver always occurs before the screen sleeps. There's no preference in Snow Leopard to only ask your password after the screen sleeps
If the above post is confusing, please feel free to ask me to try and clarify it
System Preference > Security > uncheck Require password
try that to see if it helps.
Unfortunately, this preference makes your Mac easier to obtain information in your Keychain and therefore does not help those who are complaining in this thread