Steps to reproduce:

1. Create a Toaster project
2. Build something (e.g. core-image-minimal)
3. When the build finishes, click on the target name, then on the "tasks" link on the left navigation
4. Click on the filter icon next to the "Outcome" table heading
5. Select the "Covered tasks" radio button (if you have a "0" next to that radio button, run the build again: that should generate plenty of covered tasks)
6. Click the "apply" button
7. In the list of tasks returned, click one of the task names

Outcome: the page never loads. It only happens for the "Covered" task outcome: for all other tasks, the page loads without problems.

We have seen this in the past, and if I remember correctly, it was due to the computation of the "covered by" information. See bug 6775