I am using Windows 8.1, Outlook 2010, Act! Pro 22.214.171.124 Hot Fix 1
When I enable Act! Scheduler to perform either a database backup or maintenance or both, and schedule Synchronize Service in Outlook to Synchronize Contacts and Calender at a certain time, Act! Integration Sevice crashes/closes. Contacts & Calendar will Sync, but I have to restart my PC to get Act! Integration Service running again.
With Act! Scheduler disabled, Contacts & Calendar Sync perfectly, no crash.