Ok, I've put this in Off-Topic as I think it's a laptop problem rather than a Puppy issue, although I'm not 100% sure. In fact my head is spinning at the moment. Anyway, I'll start at the beginning.
I have two portable hard drives, one with Fossa95 frugally installed and the other with VanillaDPup, also frugally installed. I've had both for some time and both have always worked perfectly well and without issue. This morning I plugged Vanilla into a laptop that I don't often use, and it wouldn't boot. After a significant delay it eventually got as far as "Probing EDD", then just flashing cursor. I left it for 5 or 6 minutes then gave up and pressed the power button to kill it.
So I then plugged in Fossa to same laptop, and that still booted ok. The Linux distro that's installed on this laptop also still boots ok, as have other distros in the past, with one exception.
Some time ago I installed antiX Linux on this laptop, and that wouldn't boot. The boot process started, then I just got a black screen with flashing cursor. I then used same USB stick and installed antiX on a little Netbook I have, and it booted fine, and everything worked.
So it's almost as though out of all the thousands of Linux distros there are just two that this laptop doesn't like for some mysterious reason, VanillaDPup and antiX.
If anyone out there has any idea what on earth could be going on, I would love to hear it.
Thanks