Hi Otto,
I am only guessing on this one but I think the files are the result of a crash during a render process. Helios is the rendering engine used in TFP and the files seem to be some photoboards, textures and .ent (entity) files, ones I think implicated in the crash.
Since the crash has already happenend I don't thin there would be any issue in deleteing them but maybe Pat or others more 'technical' than me can confirm that for us.
Allan