Equium A200 constanly losing internet

I have this Equium, which for the last few months has been constantly losing its internet connection.
It does it with whatever browser I use, and does it when using wireless or when wired to my router. It also does it with public routers. I have other computers on my network that don't lose their connectivity when this one does.
I've tried disabling addons in IE8, I've tried running spybot and various antivirals, but nothing. I've disabled all firewalls, and once when I was hung and waiting to see if the connection came back, as it very occasionally will, I went through Services shutting them down one by one to see if any affected it, but they didn;t.
I've also tried reinstalling windows (Vista SP2), but that didn;t work either.
The problem seems intermittent at first, but then gets worse and worse. Sometimes it will stop the laptop shutting down, and I'll have to take the battery out. It never crashes the laptop, though.
I have noticed sometimes that the HDD seems to be working when the hang happens, though not all the time.

Anyone have the same problem with their Equium, and anyone know how to fix it? I'm about ready to throw the damn thing out of the window.