OpenBSD 6.1 installs from DVD, but 7.6 does not.

[Fables Bookshop]

Hello,

I have OpenBSD version 7.6 downloaded and burnt to a dvd. This will not 
install to a clean hdd. My old version 7.1 will still install fine.

It fails soon after loading the file sets, they do not load fully, the 
%age count never reaches 100% and it then offers to reboot. I did a 
second download, burnt a second dvd, but the process repeats itself. So 
at this point no dmesg.

The machine had the minimum 2G memory which I have upgraded to 4G, again 
no change. I am suspecting some change perhaps rendering an older 
machine unusable.

I don't believe that I can Upgrade from the new disk so have not tried 
that. Sorry if this is a bit short on info.

I see that some of the mirrors offer iso's of earlier releases, maybe I 
should start with version 7.2 and work my way up? Looking for ideas that 
are less than desperate.

Many thanks.

Ian