Using QGLBuffer and QGLWidget::renderText problem.

Hello!
I have a problem with using QGLBuffer and QGLWidget::renderText function. I read that renderText messes with buffer objects and that they should be unbinded before rendering text. So I call QGLBuffer::release for all buffers I use. Nevertheless renderText crashes the application. Did anybody faced with such a problem? Thanks in advance.

I'm using Qt 4.7.4 for Windows with C++.