That timeout is sufficient. If you are running 7.1.2 MP1.1 please ensure that you have installed at least the v6RU (v9RU is the latest) as it contains improvements to that report.
If you are already on v9RU, then run the report with the LogViewer open as it captures the sql used. You can then run that sql directly against the database to see how long it takes to complete.
If you are running 7.5, what HF are you on?