DVD authoring - aspect ratio

I'm having some problems authoring an anamorphic PAL DVD. I'm using HCgui to encode the MPEG stream and I'm using a trial version of DVD Lab Pro to author it. It plays fine in PowerDVD and Windows Media Player, but VLC player displays the wrong aspect ratio. It outputs 2048 x 576 resolution. I can fix it by selecting 16:9 in the aspect ratio menu, but what is causing this problem? Any ideas?

That's a VLC bug/feature (depending how you watch at it). It also shows the framerate as 50 fps if you have encoded the video as interlaced

Is there a way to fix it? Also, does this affect anything other than VLC (standalone players etc.)?