Shoutbox

Can you access the folder from any other account?

If you find one that does skip to the astrexed part of this post.

If no, try booting your computer in safe mode (Start > Run > msconfig > ok > boot.ini > /safemode (check) > ok > reboot).
Open the account in the Administrator account, if it exists, and try opening it.

* Once you have an account that can access it right click on it then click on the "sharing" tab, and make sure "Make this folder private" isn't checked. Also rename it back to "Shared Documents"

If you need to get back out of safe mode. Start > Run > msconfig > ok > boot.ini > /safemode (uncheck) > ok > reboot