I'm absolutely sure that the paklog.txt file belong to UFO-AI version 2.1. On my PC there is Windows XP, Office and UFO: I don't think Microsoft's program search for a file named shaders.txt in the UFO-AI subfolders...
The log tell that the program searched the file shaders.txt and didn't found it. That was becuase it searched in the wrong folder. This problem was probably correlated to another bug that I have wrote here in the forum, in the area "bug with the 2.1 version", that caused, together with other missing files (translations file), that the game has returned to the main menu during playing.