Microsoft has a known issue with RDP access which affects the standard Windows Terminal Services Client and CloudShare's version of it as well.  

The problem manifests itself when you are: 

• connected to a VM (or any PC) remotely using MSTSC
• either in fullscreen RDP, windowed or the CloudShare web browser RDP
• actively working on your local PC, switching between different applications or screens (taking focus away from the RDP session)
• returning to RDP after taking focus away, mouse and keyboard control is locked up or appears frozen

This has recently been verified and replicated on some CloudShare VMs and there is a fix available from Microsoft.  You can either:

• run Windows Update on your PC, making sure you update to the latest version of RDP
• install the KB2579381 patch