@user181 :I'm jumping on this because I have the same issue, but the solution doesn't work.
I created a test project from scratch with only one drawing. When I open it from inside ACADE the project opens fine. If I open the project from Windows File explorer I get the dialog stating it cannot find the drawing. It doesn't say what drawing. I have to point the program to the test drawing every time.
I tried pointing ACADE to the template folder and template file, without success.
I tried STARTUP = 0, 1, 2 & 3. The dialog boxes open normally in each mode. With STARTUP = 0 the dialog still opens, but it loads the new file as drawing1 with the template. STARTUP=1 brings up the open drawing dialog box. STARTUP=2 brings up a find file dialog. However, before the dialog box ACADE always says it can't find the drawing.
I tried removing all the drawings from the project file. I also made sure the configuration files in the project were valid.
Thank you in advance for your help.