I've been successful in image files: gif, bmp, jpg, tif.
Been unsuccessful in ttf, otf, pfm, pfb fonts.
I had no problems copying these same files into Windows Explorer.
Lister columns are (file) Name, Size, (file) Type, Modified date/time, Attribute, Dimensions, Shooting time. (Last two are blank on font files). From Everything the visible columns are: (file or directory) Name, (full) Path, Size, Date Modified.
Some background: in XP (at least), there are excessively long delays when handling font files. Apparently each file in a directory has to be read, (installed?), and decoded. DOpus doesn't do that so is incredibly much faster handling fonts. (Seems as fast as any other file type). This was the reason I purchased DOpus in fact.
You can see this slug action in any program that accesses a directory containing fonts (not using DOpus). I wonder if there's any conflict gong on there?
During my testing, I frequently got this error "Access violation at address 03E23776 in module IZArcCM.dll Read of address 00000004" and this one: