The chronology of the problem is following:
1. Until yesterday I was using v.2.11 for Windows + extra loaded nodes for I/O XLS-files and Math Formula (for Math expressions).
2. Today upgraded to v.2.13 for Windows (32).
3. After upgrade extra loaded nodes (xls & Math Formula) have vanished and I cannot download them using Menu: Get additional nodes. The download prosses starts but never complets. The following error pops-up:
P.S. I tried to emulate the situation on my Mac. Upgrade from 2.11 to 2.12 worked perfectly well, moreover it didnt wipe away additionaly loaded nodes.
If somebody can help or just give a hint in what direction to dig... I will be very gratefull :)