Continous problems with vSphere client 5.1

Hi all,

I have continous problems using vSphere client 5.1 agains an ESXi 5.1 free hypervisor. Every time that I can try to "Open console", same error appears:

"The VMRC Console has disconnected .. attempting to reconnect".

vSphere client 5.1 is installed under Windows 2008 R2 (I don't use Windows 8 or Windows 2012, like I see in some threads about this problems). I have tried to uninstall all Visual c++ redistributable packages and reinstall vsphere client ... but no go.

Any idea??

Thanks