1. Set the permissions on your wp-content folder as open as you can: for me, I gave Full Modify to Users
2. Make a "temp" folder in your blog's wp-content folder.
3. Add something like the following to your wp-config.php file. Notice that the other defines chain on how you set the first one.
* Russian blogger's attempt to fix a similar issue
* Wordpress Codex documentation on wp-config.php