Backup to Network Share fails for Joomla 1.5

I'm trying to back up a Joomla 1.5 (latest version of Jumpbox) to a network share on the host PC (Windows XP, share is simply c:\backup). The network share has been set to give full permissions to everyone. Configuration status in Jumpbox admin says 'configured'.

When I click 'run backup now' it just freezes on 'Backup in Progress. Please wait'. I can see that a folder is created in the share called tmp.ulXGXRDg.ip, and a bu.tar file is also created in the share. It gets to 30MB, and then gets no bigger.

'Download backup' works fine, the total file size is just over 10MB. I've disabled antivirus, and there's a VMWare exception (vmware player being used) for the Windows Firewall.

Any thoughts? Thanks.

Help with the above

Hi, would it have helped if I logged the problem with the username assocated with my Jumpbox subscription?