Symptoms

As per K2 4.6.10 release note PowerShell v3 is a requirement for K2. But there are known compatibility issues between PowerShell v3 and SharePoint 2010 which is still in use in many environments.
 

Diagnoses

There are some issues caused by the fact that SharePoint 2010 Management Shell works only with versions 2.0 of PowerShell. This is well known issue covered in Microsoft KB article:

KB2796733 "SharePoint 2010 Management Shell does not load with Windows PowerShell 3.0"

Once PowerShell 3.0 installed on your SharePoint 2010 servers you will not be able to start SharePoint Management Shell. To workaround this you should edit properties of SharePoint Management Shell shortcut (as per above mentioned Microsoft KB):

1. 
   
2. Click Start, and then right-click SharePoint 2010 Management Shell.
   
3. Click Properties.
   
4. Click the Shortcut tab in the SharePoint 2010 Management Shell Properties window.
   
5. Input the following value in the Target field:
   
   C:WindowsSystem32WindowsPowerShellv1.0powershell.exe -Version 2.0 -NoExit " and ' C:Program FilesCommon FilesMicrosoft SharedWeb Server Extensions14CONFIGPOWERSHELLRegistrationsharepoint.ps1 ' "
   
    

There is also an alternative workaround which suggest to force PowerShell to globally use a different CLR. Please refer to the following URL for details:
http://www.wiredinit.com/sharepoint-2010-vs-powershell-3-0/
 

Resolution

Please use above mentioned workaround which is based on Microsoft KB2796733.