Mail was unable to save the attachment

After installing leopard I cannot open any attachment. I get this error on every email I get with an attachment: Mail was unable to save the attachment “image.jpg” to disk. Verify that your downloads folder exists and is writable.

Of course I checked my downloads folder exists and is writeable, I even tried creating a new folder and get the same error.

Obviously something with the Leopard install because I was downloading attachments right before that.

Please help!! I can't download any of my clients email attachments!!

thanks,

Jeff