Okay, problem solved. I used TotalCommander to view the registry keys, and found that there was no "Shell" key in PVB.ProjectRun
(which would include the subkeys to point the system to pvb.exe to open the apps
). Instead this key and its subkeys were under the ".pvb" key - but with no value entered under Shell/Icon/Command. So I entered the keys manually under PVB.ProjectRun, reading from my PA-2400U's registry, and deleted the subkeys from the ".pvb" key. Lo and behold, each of the .pvb apps then opened when tapped on. Another error in PVB.ProjectRun, though: for some reason "DefaultIcon" was a string value instead of a subkey, while it there was a DefaultIcon subkey under .pvb. So I created the DefaultIcon subkey manually under PVB.ProjectRun, and entered the value given in .pvb/DefaultIcon: a default string value of "\Windows\pvbrt.dll, 1." Then I deleted the DefaultIcon subkey from .pvb. At this point, however, the apps were still represented by the generic Windows icon. I checked my PA-2400U, which had this value as "\Windows\pvbrt.dll, -2." So I changed the value on the 360LX to that, and now the VB icons appear for these apps.
(pant, pant
)
Wonder why the registry entries were wrong, given that I hadn't installed any VB/PVB-based apps on the 360LX before or since copying the runtime files and .pvb files to the device.