"When opening Organizer within BlackBerry Desktop Software 6.0, the calendar shows as not installed."
Blackberry has a temporary workaround:
Perform the following steps:
- Back up the data on the BlackBerry smartphone. See KB23680.
- Delete all data and applications from the BlackBerry smartphone using the Wipe Handheld option. See KB14058.
- Restore the data to BlackBerry smartphone. See "restore data' in KB23680 link above.
- Connect the BlackBerry smartphone to the computer and open the BlackBerry Desktop Software.Calendar (not installed) will no longer be present.Source: http://www.blackberry.com/btsc/search.do?cmd=displayKC&docType=kc&externalId=KB23978
3/21/2011 - This still works and is the only method I have found to 'fix' this issue.