Notes about the DTR file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The DTR file type is primarily associated with 'DiagTransfer' by alain Blaisot. DiagTransfer is a program that allows you to transfer chess diagrams. .DTR files are a special DiagTransfer format; the program can also output FEN or EPD formats as well as pure graphics.