InfoPath Dev

Hi, I am having a strange problem with attachments field on a list InfoPath form. The attachments get uploaded successfully but not able to access/open any attachment uploaded by someone else, on the form. The error says "The file is corrupt or invalid". It is happening for all the file formats...

I've been trying to get the value of a check box in a sp list. so, I have List[a] and List[b]. List[b] contains a check box which I am trying to get the value of inorder to put in in List[a]. I'm using Infopath 2010. I've tried doing this by using a ckbox in List[a] -- that did not work....