Can’t attach files to e-mails in windows live mail

I recently tried to attach a file to an e-mail using windows live mail client but when trying to do so a dialog box popped up saying I didn't have permission to open the file. The same happens for any Microsoft Word or PDF files. There seems to be no problem with Excel, text or xps files. The same is true if I try to do it by right clicking on the file and using send to mail recipient. Excel, rtf and xps files work fine but live mail doesn't even open with Word and pdf's. This is extremely frustrating. Does anybody ahve any idea what the problem is or how to solve it?