Right, I did observe good static precautions, being in electronics design and proto building I have the necessary stuff, wrist straps, mains lead with only earth connection etc.
Excellent, if only everyone did....
The machine boots up and stays up as long as the wireless network is not enabled. I don't have any applications that I can leave running to test everything stays good.
A trivial test that never completes is easy, but it won't thrash the memory & disk enough. I kick off graphics tasks that take up to 12 hours, but there's gigabytes of raw files involved. I think the answer is elsewhere though....
I have run the Ubuntu memory test and it goes through the 6 Gb of ram repeatedly without error. As soon as I enable the wireless network it becomes unstable and reboots at irregular intervals, from a few seconds to 20 minutes.
Yeees. The card and its interrupts (ISA card I assume), or its driver come under suspicion now.
It has connected and downloaded a few (200+ !) updates for Ubuntu
That's the way Linux updates & fixes work: little & often. Unlike the Windows way of huge and yearly. (Server-grade Windows is monthly updates -- look up "patch Tuesday".) If your e.g. office, multimedia or graphics applications came through Ubuntu they get updated at the same time automagically, so you don't have to go round all the vendors to find their latest patches.
The wireless card in the new system is a known working card pinched from an old, but still working, desktop machine.
This morning I swapped the wireless network cards between the new system and my Dell desktop, which I am using for this browsing session. This was fruitless as neither machine had the correct drivers for the cards so I have swapped them back.
Linux does suffer a real problem with add-on cards. The developers often refuse to sign their rights away to see the proprietary information needed to handle the card, and the manufacturers can't be bothered to provide proper Linux drivers. So the result is that someone takes a flying guess at how the card works. And that can result in problems. If you absolutely have to have wireless networking I'd research what vendors provide proper Linux drivers and get one of their supported cards. If it's not an absolute necessity then you'll improve your security (or save yourself a lot of work setting it up properly) by reverting to a wired network.
I have no need of wireless at home, and have in the past refused to countenance it for businesses, unless the hours (weeks?) of research and experiment into how to configure it securely could be resourced. I was paid to be paranoid, and I think I did a good job ;-)
in /var there is a "crash" directory with 3 files in. I'll search through them and dmesg to see what they reveal.
/var/crash is empty on this Ubuntu system :-
uptime 20:13:03 up 60 days, 3:07, 4 users, load average: 0.01, 0.03, 0.00
... so hang on in there, the problems are not unsolvable.
'b