Hello PSPad doesn't change any system extensions like EXE, BAT, ... PSPad uses PPR as PSPad Project extension and on request it can handle TXT files. No other extensions.
Please don't assign files like BAT, EXE to PSPad in program settings / Registered files types. It assign files directly to PSPad and in case of executable files it will break their functionality. It's similar as you will assign them to open in Acrobat Reader. If you want to edit BAT files, drag / Drop them into PSPad or use right mouse and Edit in PSPad -- <https://forum.pspad.com/read.php?2,72545,72546> PSPad freeware editor https://www.pspad.com
