I had SO many problems with files being corrupted or lost when going through and editing multiple document files in a folder, especially multi-page TIF and PDF files. I even submitted bug reports and looked for solutions. I finally had a flash of inspiration: the folder I was editing in was being synchronized with other computers. When I moved the files to be edited to a folder OUT OF the synchronized folder, my problems went away!
If you are using Dropbox, Resilio sync, or some other file synchronizer, it may try to sync your file in the middle of the write process when IrfanView is saving the edited file and cause corruption. Moving (or copying) those files to a non-synchronized folder may solve your issue.
If you are using Dropbox, Resilio sync, or some other file synchronizer, it may try to sync your file in the middle of the write process when IrfanView is saving the edited file and cause corruption. Moving (or copying) those files to a non-synchronized folder may solve your issue.