Right click the folder, and go to Properties.

Is the read only button checked? If so is it greyed out or a full on black check mark?

This article might apply:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;326549

Also go into the security tab. Go to the bottom and click advanced.

In the resulting box, click "Owner" and see if your user name is listed.

Even if you see your name click "Edit" and in the resulting box highlight your user name and check the box below that says "Replac owner on subcontainers and objects"

Click Apply and OK....let is chug till its done and try again.

Let me know either way.

Roman