I am not familiar with protect or this issue, but it may be beneficial to rule out the protect application by running a similar WMI query against your target windows guests manually. Keep in mind that WMI will not communicate with linux (of course) and may need extra patching on older Windows operating systems to work.
http://blogs.technet.com/b/bshukla/archive/2010/12/09/powershell-script-to-report-uptime.aspx
