This is generally caused by the damage of encryption information file. If you encountered such situation, please press OK and solve it according to the instructions on Best Encryption Expert.
For trial version users, please click OK and enter the password "www.dogoodsoft.com", and then click the Unprotect button.
For full version users, please first click the Settings button to set an admin password, and then use the password to unprotect your folder.
The unprotected folder may be saved to the disk root directory.
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