经过一整天的麻烦，我们找到了答案.我们仍然不确定到底为什么会发生，但是powershell目录从Hudson的路径中消失了.然后，尽管安装了PS3并重新启动了计算机，但由于某种原因，Hudson并未选择新的PATH变量.

After a day's worth of hassle we found the answer. We're still not sure exactly why it happened but the powershell directory disappeared from Hudson's path. Then, although PS3 was installed and the machine had been restarted, Hudson for some reason had not picked up the new PATH variable.

手动关闭并重新启动Hudson最终使它能够选择正确的PATH并解决了该问题.

Manually shutting down and restarting Hudson finally got it to pick up the correct PATH and fixed the issue.