The entities of the block were probably originally drawn on layer 0, and on explosion they have migrated back to this layer. Check whether layer 0 is switched off or frozen, and if so, thaw and switch on. If entities are then visible, they can be selected and moved to a chosen layer.
The kts_productname is set in a file called acaddoc.lsp. This file is only found in the R20 (or R19/18) folder in the installation folder. It is found using the Support File Search Path setting in the AutoCAD profile. If another file is found before the one in the R18 etc. folder then GuideSIGN Markings cannot load the menus or start the program properly.
Layers containing the road layout and other features have been switched off - simply use AutoCAD's layers features to turn on the layers you want to see. If this happens repeatedly, you can edit the file DEVLAY.ON to include additional layers to be visible by default in Driver's Eye view.
GuideSIGN Markings program files not loading correctly – double clicking a Dwg for windows doesn’t start GuideSIGN Markings properly, always use the desktop icon to start.
Another ACADDOC.LSP is being loaded instead - check that there is not a file of this name in the working directory taking precedence.
If these are standard AutoCAD fonts, then the ACAD search path probably does not include the FONTS directory - see installation instructions. If these are KeySIGN fonts, and you have KeySIGN available, you can direct AutoCAD to find them or copy the font files (suffix .shx) to the GuideSIGN Markings directory. If they are other fonts that are not available to you, you can substitute a different font.
The working menu has become corrupted. Go to GuideSIGN Markings Tools > Program + Options > Reload GuideSIGN Markings.