This error shows that the Zoiper process has stopped working and Windows is displaying it.
This issue can be caused by some antivirus applications for example.
When Zoiper crashes we recommend that you try to gather both debug-log and crash-log files and send them to us for investigation.
You can find information how to create both files here: https://www.zoiper.com/en/support/answer/for/windows/75/Log_files