1. I got message "File may contain overlays! Do you want to continue anyway?" What does this means? What should I do?

PC Guard for Win32 can handle executable files with or without internal overlays. The warning message is for security reasons. For example, if you are trying to protect application with debug information attached to it you will be warned (it's not too good to distribute debug version of your application). On the other hand, some executable files are checking the structure of internal overlay so it is good to warn user that he is going to protect application which contains internal overlay. In general, if you get above warning message and you are not sure what you should do, contact us with detailed information about application you are trying to protect.

2. Can you explain more about "Remove overlay from executable file" option? When shall we enable it?

If this option is set, internal overlay will be removed from application file. Overlay may contain any data but usually contains debug information which should be removed after protection. Some files will not work if internal overlay is removed as it contains information which is crucial for application. Most files are without internal overlay, though.

3. Does PC Guard for Win32 still encrypts protected application with password string, in the case we enable "use password string for file encryption" and enter "password string" but disable "Password Protection"?

No. This option is valid for password protection method only.