Windows XP Access Denied error on C: share when Administrator

This can be caused by Simple File Sharing being enabled on Windows XP. You can switch this off using the following steps.

1. Launch Windows Explorer.
2. From the Tools menu, select "Folder Options...".
3. In the window that appears, select the View tab.
4. Scroll to the end of list of options and clear the checkbox "Use simple file sharing (Recommended)".
5. Click OK to close the window.
6. Reboot your PC.