I made an httpjob GET request with jhttputils2 ver 1.03 and i got the error:
gen 15, 2015 12:49:21 AM org.apache.http.impl.client.DefaultHttpClient handleResponse
Make sure that your can login dropbox with chrome/firefox.
Try a new java version may help.
If cookies are set by server(dropbox.com), remove/set them will not solve this.
This may cause by jvm webview. JVM webview are reported with some bugs (e.g. it can't load b4x.com )
If you can upload the project, someone else may help