I'm managing a subversion server with access via http using webdav. I've observed that after I access the repository having a browser, sometimes the pdf files within the repository appear as plain text (just like you seen the pdf having a text editor like emacs, vim, or notepad) rather than being downloaded, or opened up with a few pdf readers. Should you save the page, then open it up having a pdf readers, it really works fine. Any ideas why this can be happening? It appears to become somewhat browser dependent, and does not happen with all of files. The file below appears to possess this issue a great deal though: http://robfelty.com/subversion/ling5200/slides/ling5200-all-notes.pdf

Set the svn property svn:mime-type to application/octed-stream, or even better to application/pdf.

Maybe the file has got the wrong mime type? It ought to be something similar to "application/octet-stream".