Issues such as AccountEdge crashing or being unable to backup can be caused by your Trend Micro software. Termination Code 1264 is commonly seen when using Trend Micro and your AccountEdge software.
To determine if Trend Micro is affecting AccountEdge, temporarily disable Trend Micro and see if it fixes the issue you're seeing in AccountEdge.
If you continue experiencing issues with Trend Micro, contact them for assistance.
