I had the same problem. Look https://community.xibo.org.uk/t/xibo-1-8rc2-player-build-with-target-net-4-0-for-windows-xp-sp3/8226/3
This error report is because xibo player is built under .net 4.5 framework.
.net4.5 is not supported by windows XP.
I can confirm that you can rebuild 1.7.9 xibo player (and watchdog) in Visual Studio 2013 by changing .net platform to 4.0 and executing command in NuGet console to update all packages built for .net 4.0.
About 1.8rc3 - i don’t know - as it is probably rely on EmbedIO package, which has no bulit under .net 4.0.
Also in your kiosks: update your XP to SP3, update Internet Explorer to the latest XP supported version, install the latest .net XP-supported version (it is .net 4.0.3).
I can make mistakes, because don’t remember this well. But our XP sp3 embedded TV box works perfect with rebuild .net 4.0 xibo (1.7.9). Every day it shows videos in full screen mode.