I got this error in firefox when I tried to upload multiple attachments. I then also got this area on another occasion when I uploaded and attachment but realised it was the wrong attachment and uploaded the correct one and got the error. Though each time I try to upload multiple attachments this error occurs everytime. Using firefox 10, not sure whether that is how the RM is "designed" to work or a bug but thought I'd mention it since it was the same error I got several times