I am also using Outlook 2010 and use multiple calendars..However, when i select one calendar, the others don't fade as if i had selected some opacity setting.

So i can help you troubleshoot this, supply some additional information and steps.

- Do you have each calendar checked?
- What view type do you have your calendars in?
- When you select one calendars do the other calendars become unchecked?

Best Regards.