Based on my local test, I can sync WSS 3.0 calendar with Outlook 2010. First, make sure you provide the right account and credential when you sync WSS 3.0 calendar
to Outlook 2010. This account may not the same as the account you login into the WSS 3.0 site.
Second, make sure the account you login into the WSS 3.0 site has enough permission on the site and calendar list.
Finally, try to use site administrator to login into the WSS 3.0 site, then create a new Outlook 2010 profile with the same account, then check the effect.
For more information about create a Outlook profile, please refer to the following article:
Support in forum
If you have any feedback on our support, please contact