NV+ slows after 15-20 minutes [SOLVED]

Right, I managed to get the fixed IP without any difficulty. First I created the .tib file, which took between 90 and 105 minutes. It completed without errors. My network stats after the backup were as follows (I forgot to reset the counters before running the backup) :oops:

Auto-negotiation 17
Bad packets 0
Disconnect 13
False carrier 1526
Idle errors 20727
Link failures 0
Receive errors 0
Symbol errors 124
VLAN tags 0
TCP Retransmits 17
Unrecovered TCP Retransmits 7

Then I tried to do a restore, having reset the counters.

It behaved exactly as before, with the job starting well and after 5 minutes running it said 1 hr 39 minutes to complete the job. After 1 hour I went back to check and there was a poor media quality message, with 52 minutes remaining. I clicked through a couple of times for further attempts to get the data, but the error message came back after 6-30 seconds. My best guess is that the job ran fine for 30-40 minutes and the crashed. Network stats were as follows

Auto-negotiation 2
Bad packets 0
Disconnect 2
False carrier 1205
Idle errors 5180
Link failures 0
Receive errors 0
Symbol errors 36
VLAN tags 0
TCP Retransmits 14
Unrecovered TCP Retransmits 5

I have just checked memory usage and 45 minutes after cancelling the restore chached memory is still at 86% meaning 98% of RAM is allocated

Does this help point the finger in any direction ??