Computer restarts in the middle of consolidating backups

I am running Acronis True Image Home 2009 on a virtual Windows XP Professional machine under Parallels on an iMac. There is a daily job to backup changes to the virtual machine overnight. Periodically it reboots the virtual machine in the middle of consolidating the backups. They are being done to a Buffalo LinkStation.

At first I wanted to ensure that this was not a Parallels issue but now I am thinking it isn't even related to the backup software but rather to some network error or possibly a problem with the LinkStation. The reason I suspect this is that I am also running a weekly backup from another Windows XP Professional machine on a weekly basis (Saturday mornings). Yesterday neither system rebooted in the middle of the consolidation (indeed the native machine never has) but both experienced problems reading their respective files on the LinkStation at 2:18 a.m. The error in both cases is, "The specified network name is no longer available." The fact that it happened on two different machines at the same time indicates that it isn't the software nor the virtual machine with this particular error.

Just to be sure that I am dealing with only one issue and not multiple issues, my question is whether the error about losing connectivity to a remote saving location can cause a restart. A significant difference between the error I see when it didn't reboot and when it does is that when it reboots the last message in the backup just says it has the consolidation location identified but nothing happens after that. Whereas with the error yesterday the backup keeps trying to contact the storage device.

So are both of these symptoms of the same problem or different problems? If they are the same it seems to point to either a network problem or a NAS problem. If different then why would a reboot happen sometimes?