Bit of a long-shot but I've tried googling this with no joy. Has anyone else had this problem?

In the office we've got Sony Vaio laptops, I want to hook an external monitor up to mine but when I do the picture is very flickery but ONLY when the AC adaptor is plugged in. When it's running off battery power then there's no problem. I've tested several monitors of differing makes and specs and they all have the same problem. I've also tried on the other Sony laptops in the office (all differing models), some of them have the same problem, some of them don't.
The thing the affected models have in common is the AC adaptor: all run at 19.5V but have differing ampages. The models that have 6.2A adaptors have the problem, those with lower ampages don't. If I plug one of the lower amp adaptors into my laptop then the problem goes away but I don't think this will do the laptop much good.

I can't believe that all Sony Laptops that have this particular AC adaptor will have this problem but that's the way it seems from my tests in our small office. Anyone got any ideas how to fix this?

Your deffinitly using the correct AC adaptor for that model?
Have you googled it? seems a bit strange.

Yeah, I'm using the one that came with it. When I googled it I found one person having the same problem but no solution. I'd have expected to find loads of cases if it was a common problem. As I say though, it isn't just this one model a couple of them have the same issue. It's very odd.

Clearly a problem with the adaptors then, I'd contact Sony.

Yeah, I'm going through their support process at the moment. So far they've suggested bios and driver updates. Can't see either of those fixing it somehow. I can't believe they don't know about this.