XP is built on a windows NT core, a network OS, it this a basic security/sharing measure built into the os. Poser has files open in the folder and thats why it won't rename most likely. Try a simple experiment 1.copy a picture into a newfolder on your desktop, then open the photo 2. while the photo is open in photoshop or whatever, try to rename the folder it is in, and it won't let you. This is a basic function of the network OS to keep 2 seperate users on a network with acess to the share from updating the same file at the same time, one can read the file while one works on it. It also is part of what gives NT based OS's more stability than 95/98/ME. I don't believe there is or should be a way to circumvent it, as it would undermine the stability of the OS itself. Just my two cents, I'm not a programmer or anything, just a network admin.
Zerowolf