I just downloaded the main part from the tracker into my Unofficial/Parts directory, then opened the file without errors or warnings. LDView automatically downloaded the sub-files (including x581s01.dat and x581d02.dat) from ldraw.org while loading the file. I checked the dates, and both those sub-files were created today, so neither pre-existed on my hard drive. I did all this with the official LDView 4.1 release running on a Mac, but I wouldn't expect the results to be any different on Windows.
Note also that the Parts Tracker itself uses a Linux command line build of LDView to display parts on the tracker (with auto-downloads disabled), and the part image for the part looks correct. Philo did say that ldraw.org was unreachable for a while recently. LDView will disable automatic downloads of unofficial parts if it has network problems while attempting to do so. Check the Updates tab of LDView's preferences, and see if "Automatically check ldraw.org for missing parts" got unchecked.
Note also that the Parts Tracker itself uses a Linux command line build of LDView to display parts on the tracker (with auto-downloads disabled), and the part image for the part looks correct. Philo did say that ldraw.org was unreachable for a while recently. LDView will disable automatic downloads of unofficial parts if it has network problems while attempting to do so. Check the Updates tab of LDView's preferences, and see if "Automatically check ldraw.org for missing parts" got unchecked.