Thanks for offering help.

Yes, the problem occurs if I use the GetOpenFileName API, exactly the same as when I use the common dialog control.

There is no difference between the IDE and compiled versions.

It affects all folders, and I don't have any ending with a period. For example I might see

?inetp.. ?wwwro.. ?cgi-b..

following the drive letter.

The dialog style flags don't seem to make a difference.