"Cannot load module DEVPTS"
This means that either devpts is not compiled into your kernel or has no entry in /etc/fstab, or both.
"So I have no idea what that module is, or what it does"
devpts is a new way to keep basic information about devices. I think that the kernel developers plan to replace the /dev logic with devpts logic.
"I assume I should be loading it "
So far very few device drivers have been written or rewritten to use devpts instead of /dev. If nothing fails because devpts is missing then you are not using it and the error messages are merely a nuisance.
Be prepared. Create a LifeBoat CD.