Click the Start Orb, then All programs, then Accessories. You'll see Command Prompt near the top of that menu. Right-click on Command Prompt and select "Run as administrator" in the dropdown menu. You'll either have to enter the password, or just click OK if you are logged on as a member of the Administrators Group.
When the command window opens, type the drive letter of the location of the folder in question, and hit enter.
Next type "attrib -h <folder name>" (without the quotes) and hit the enter key.
If it works, you'll just see a blinking cursor. If not, you'll see an error message. If you get an error message, post that back here. If no error message, type "exit" (without the quotes) and hit enter.
Now try to take ownership again.