我需要在Server2008R2上，用NSIS调用powershell来判断Desktop-Experience是否已安装，如果没有安装，则安装它并重启。我做了一个测试程序，在第一步Import-Module时就出错： 
!include "x64.nsh" 

Name "nsExec Test" 
OutFile "nsExecTest.exe" 
ShowInstDetails show 

Section "Output to variable" 
${If} ${RunningX64} 
${DisableX64FSRedirection} 

nsExec::ExecToStack 'powershell.exe "& "Import-Module ServerManager"' 
Pop $0 # return value/error/timeout 
Pop $1 # printed text, up to ${NSIS_MAX_STRLEN} 
DetailPrint '"ImportModules" printed: $1' 
DetailPrint " Return value: $0" 
DetailPrint "" 

${EnableX64FSRedirection} 
${Else} 
${EndIf} 
SectionEnd 
错误信息为“Access to the path is denied”。请问这是什么原因呢？ 
我在stackoverflow上的问题链接http://stackoverflow.com/questions/13391340/how-to-call-powershell-in-nsis