HTTPTest app and Zero-Pain-Error

I have written a small utility to make use of the httplib from Chris Mahoney . It is more or less a frontend for the library. It allows you to send http requests with different verbs (GET, POST, DELETE, …) and headers. You can also view and save the response. I mainly use it for testing REST interfaces. I plan to make it publically available soon including the C sources. However, there is a zero pain error whenever I send a request which I would like to fix before making it available. Unfortunately I don’t have enough experience to find the error and hope you can help me. You can find a beta version including the source code here for download