Ethernet connection dropping

[#1]

On my 3rd Thomson Gateway TG 585 v8 in less than 2 months and new one having similar problems since switching to Plusnet in Dec..
Ok, 2 computers (Widows XP Pro & Windows 7) connected via individual cables to the router. Initially, all ok for  a few weeks, then, both computers lost ethernet connection (Ethernet light OFF). Got a new router, ok for 9 days, then, same disconnection problem (This time, Ethernet light ON). Got another new router on 18th Feb, ok for 12 hrs, now the same problem AGAIN (Ethernet light ON). So, being sent a 4th !!!!
Using the power reset button  is no good, only switching off at the mains for 15mins seems to work and this one, that I,m struggling with, will not even reset  via the paper clip hole.
I have a choice of Ethernet or wireless on my computer (XP) and when Ethernet drops, I can't even see the router  in my wireless networks, yet I can see other wireless networks.
Am I just being unlucky, or are Thomson' s just rubbish?

[#2]

Hi there,
I'm sorry to hear about the repeat problems you've had here. I'm not sure what the issues may have been with the router's you've had (maybe a faulty batch) but IMO I see no point in sending a fourth v8 at all. I've cancelled that order and have dispatched a Technicolor TN582 which should reach you within a couple of days.

[#3]

It might seem a long shot but have you tried different ethernet cables?
I've known of one case where a faulty cable was prime suspect in random router reboots.  Not sure whether a faulty NIC on one of the PCs could have a similar effect but maybe also worth trying to eliminate.

[#4]

Thanks. Got the new router today.  Must say, took some time setting up, and seems to be ok at the moment. See how it goes. Odd thing is, that the old router had behaved since reporting, after varying resets
The thing I  can't get, is, that when I reported the last reoccurring fault, with the newly supplied, Thomson Gateway TG 585 v8, I asked if there was a different router available, and was told, NO!  But you came good,  to my mind, with what will be, the new,  general supplied router, now that IPv6 is on it's way.
Thanks again,
D