not write temporary file

[Lynne]

The only folders you should have chmod 777 are the ones vbulletin tells you to chmod to 777 and this is one of those cases. From the help button in the Avatars area in the admin cp:

If you are moving images into the file system, you will need to create a directory within your forums folder (/images/customavatars is a good one) for their storage. Unlike when you are storing attachments in the file system, this folder must be accessible from the web (usually CHMOD 777).