Thanks Karl.
I checked that folder, and the links within it to web addresses are all there, and all work using default browser when clicked on, even though they don't when clicked within ArchiCAD.
The PDF help files are all present in the ArchiCAD program/documentation directory , and though the links to them that normally appear under the help menu still show, they no longer work.
As if the drop down menu links are damaged, rather than the files linked to.
I tried removing & restoring the help menu via the work environment dialogue, but no improvement.
PAUL KING | https://www.prime.net.nz
ArchiCAD 8-27 | Twinmotion 2023
Windoze 11 PC | Intel Core i9 10900K | Nvidia Gforce RTX 3080 | 32 Gb DDR3 | 2x4K monitor extended desktop