Unable to download files with http profile assigned to VS

If I may add, Mel you're absolutely correct. For one reason or another the HTTP profile is issuing an error. You might also be able to see this error in the LTM log when it happens:

tail -f /var/log/ltm

Whether it's a 401 response, a webdav request, or something else that the HTTP profile doesn't understand, you need to be able to distinguish it from other requests and disable the filter. Worst case, and I mean absolute worst case, you can do the content switching in a TCP or SSL event and remove the HTTP profile completely, but it'll be more work.