virtualbox.org

If you have a linux guest os, and your apache DocumentRoot is in a shared folder using vboxsf, you will experience zero-length responses to non-zero-sized files.

If you increase the loglevel in httpd.conf to info you'll see:
Invalid argument: core_output_filter: writing data to the network

The fix for your problem is here: http://httpd.apache.org/docs/2.0/faq/er ... r.sendfile

This is because virtualbox only has a partial filesystem driver implementation.

I'm assuming subversion has the same problem type of problem when it outputs:
Can't write to file 'TRUNK/.svn/tmp/entries': Protocol error

BTW: vboxsf, is that a typo? It's a crappy name for a fs, I hope it's renamed to vboxfs _very_ soon.

I'd just like to thank you for this post, I spent hours trying to figure out why this was only happening with apache!

BTW: vboxsf, is that a typo? It's a crappy name for a fs, I hope it's renamed to vboxfs _very_ soon.

It stands for VBoxSharedFolder. I would not hold my breath waiting for it to change.