CA ArcServe: Unable to map the VM volume to a VM disk image file

Hi,

Although this isn't strictly a VMware issue i was wondering if anyone could help me out.

My VMware RAW backup using CA Arcserve 12.5 has started to fail with error:

AW0551 2010-02-15 12:13:03 Unable to map the VM volume to a VM disk image file. (VM Volume=[C:\])

and

AW0004 2010-02-15 12:13:04 . RC=110, The system cannot open the device or file specified.

Has anyone seen this before?  The help file points to permissions for the second error and missing files for the first neither seem to be an issue.  It doesn't make a difference which Host the servers are on.  I have tried using domain Admin credentials.  I dont believe anything has changed on either the ESXi host or the Proxy\VMware  Vcenter server.

any idea?

thanks for the help.