[arch-general] Pacman problem. "error writing to file" "bad address"

[Nigel Henry]

I had problems with ocaml yesterday. After the machine locked up during the 
updates, I did a hard reset, and ran pacman -Su again. It continued 
downloading ocaml, but when all the updates were downloaded, it failed to 
install them, claiming that ocaml was corrupted. I removed the corrupted 
ocaml as requested, and as I'm on dialup and didn't want to download 38MB of 
ocaml again last night, I temporarily added an IgnorePkg line for it.

Ran pacman -Su again, and all the updates apart from ocaml, and also gnupg2, 
which couldn't be found, were installed.

Today I went to install the ocaml update, having removed it from the IgnorePkg 
line. It starts to download, but then throws an error as below.

error:  error writing to file '/var/cache/pacman/pkg/ocaml....'  :Bad address

Harddrive partition is redlining, and the partly downloaded ocaml file shows 
as 2GB size.

Any ideas on a fix for this problem?

As an aside, pacman was updated, but not before the other updates, in case 
that is what has caused the problem.

Nigel.