https://bugs.winehq.org/show_bug.cgi?id=44721
--- Comment #3 from Stan markau0@lycos.com ---
From debugging it seems like a command line argument parse error.
The c:\windows\notepad.exe command line argument is getting passed to GetFullPathName as c:windowsnotepad.exe where the single backslash \ characters are parsed out by the command line parser before it reaches the GetFullPathName function (or any function for that matter).