XnView Classic for Version 2.52.2

[Lintech]

Hi, I got a new computer, and the software was updated. I cannot open a c4 file anymore. I keep getting a pop-up message saying" Format of the file could not be determined. For displaying of less common formats, the following option is available: Options>General>{x}Display all image file types.

Can someone please help me. I cannot not open any files in C4 format.