"Access denied" for random files and folders

I am the administrator on my computer.

When I extracted some folders from WinRAR, the folder suddenly would not
allow me to do anything to it---rename it, enter it, or delete it, and
telling me "Cannot delete (folder name): Access is denied. Make sure the
disk is not full or write-protected and that the file is not currently in
use."

This also happened to a file I extracted now stuck in My Documents, as well
as a shortcut I moved from the desktop to My Documents.

This is a very serious problem as no anti-virus or anti-malware program I
have, from Spybot to McAfee Sting to Norton Anti-Virus to Ad-aware will
detect something wrong with the files, and Norton won't even touch the files,
saying it cannot access them.

Just now, I was suddenly able to delete two of the four folders suffering
this affliction but only two of them.


What is wrong with these files and folders?! Why is it doing this? It's
never done this before!!!

I should also make a note that if I extracted the compressed file to a
folder of identical name to the file, extracting the folder into another
folder, both folders would be accessible, but if I were to drag and drop the
folder from the compressed file into the Windows Explorer, the folder would
deny me access.

I have also tried restarting the computer in Safe Mode and logging in as
both Administrator and my own name (also an administrator) to try and delete
the files but the problem persisted.

Update: I have found a way to delete the folders. By opening Properties and
making the folder shareable (which it then says it cannot, because of Access
Denied and such), the folder and its contents suddenly become accessable and
I can delete them


Unfortunately, there is no such option for the two files I cannot delete.
Can someone please help?