Seems to be a common complaint and usually caused by trying to upgrade and skip several version changes. fldigi maintains it's configuration (long term settings) and status (state on last execution) files in its own files folder.
|Operating System||folder / directory|
On Linux and OS X you can can create a link to the hidden “.fldigi” folders:
$ cd $ ln -s fldigi.files .fldigi
Delete these two files located in the files folder: fldigi_def.xml and fldigi.prefs
It is not necessary to delete any other files or folders. If you do then you will probably lose your macro and logbook files.
Start the new fldigi and you will be presented with the start-up wizard.
You should disable all Windows power saving features, including
* USB devices * Disk drives * Serial devices * Keyboard / Mouse i/o
All versions of Windows will disable idle devices (or devices the OS thinks are idle) from XP on, but Windows 7, Windows 8 and Windows 10 are notorious for this dis-service. You should recheck these device settings whenever the OS is updated. Someone in Redmond should be neutered.