The “Widescreen” thingy has a number of pitfalls and you have added another.
1. Widescreen begins with the shoot. A SD camera (or HDV in DV-Widescreen mode}. The PAR for PAL is 1.422.
2. Edit in a SD Widescreen Project Preset.
3. Export as Widescreen.
You did #3 right, but not 1 and 2.
#3 inserts a tag into the video that “some” DVD players catch and adjust the playback accordingly. Others require the viewer to select Widescreen using the remote.
Best bet is to import your HDV footage into a 4:3 DV project, scale it down to fit on the screen and encode as 4:3. The quality wont be quite as good as if shot in SD and the render times will be long.
Better bet is to burn it to a Blu-ray and enjoy HD on a nice TV.