SYMPTOM:
An end user exists that only has Web Report privileges in Web. Additionally, the user has their drilling preferences set to 'Open drill results in a new window', as shown below:

Now the user runs a report and decides to drill down on a specific element to the next level down. When doing so a new window opens as expected. However, if the user closes that window and decides to drill on the same report but on a different element, then when the new window appears, the following error is received:

Job Expired
The results for this report are no longer available. Please submit the request again.
CAUSE:
For this particular user with only Web Report privileges, every time a new report is opened, the previous report is no longer available as the user does not have the Web Analyst privilege of 'Web simultaneous execution'. This limits the user to one document or report instance that may stay available in memory on the Intelligence Server for manipulations. As soon as the user drills to the first drill report, the results from the original source report will no longer be available, and only the drill report is available on the Intelligence Server. Therefore, even if the user closes that browser and goes back to the report, the user can expect that the source report is now unavailable as a live report anymore.
ACTION:
In order to be able to drill a second time on the same source report, the user will need to have the 'Web simultaneous execution' privilege from Web Analyst.