That's a new one. Let's hear a lot more detail.
Your title is one thing, your post says another. I guess that's a typo but there are many causes for read only. For Apple's it's some NTFS formatted drive, for PCs it can be an corrupt volume or other.
I have installed a 2e HDD in a caddy. it showes up but it stands on write-only. how do i change it?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic