There's about 250Gb spare disk space on the PC and it uses an Intel core i5 processor, WinXP SP3 and the file system is NTFS
Unfortunately it's impossible to tell whether a particular file is causing the issue - the whole contents of the device HD are sent in on big file. I wondered whether there was some limit (such at the FAT32 4Gb limit), but cannot find any information.
I don't even know what OS the source device actually uses - nowhere can you find the information.