The open_basedir restriction keeps php scripts from writing where they're not supposed to:
http://us2.php.net/manual/en/ini.cor...i.open-basedir . In the vb settings under "Server Settings and Optimization Options", there is a setting for "Safe Mode Temporary Directory". You either need to set that to a directory that's "in the allowed path", like it says in the error message, or else change the php.ini and add C:\Windows\Temp to the open_basedir setting (I don't know much about setting up servers, so I don't know if that second option is a safe thing to do or not).
This is also an issue for uploading files - you might have to set the "Safe Mode Upload Enabled" setting to Yes, and if you're storing files in the file system, that directory will also need to be in the open_basedir path.