We are unable to login to any accounts on a Winxp Home machine. All accounts, (even the admin account when booting in safe mode) get to the welcome screen, and then it will say "Saving Settings" and then kick you back out to the login screen again.

Doing some searching, I've found this problem, and how to fix it, but it involves logging in as an administrator. Like I said, even admin gets kicked out in this fashion.

Repair install may be in order:

Here's the official Micro$oft way of doing it,
And Here's one with screen shots.

Basically this installs windows over the top of your current setup.
So you don't loose any information you already have.