Acronis True Image Home 2009 and Windows Vista Professional

Hello,

I have two Vista PC's with Acronis 2009 installed on it.
One had Vista with SP1 and the other has SP2.

The back-up works fine on the SP1 installation of Vista, but the SP2 one keeps having problem to back-up to a netwerkshare on a Windows 2003 Server (No Active Directory, Workgroup configured).
It won't authenticate in any way.

Is this problem known? Any tip or help is appreciated.
Thanks in advance.

kind regards,
Stefan