This problem is due to a faulty form control (3rd party toolkit) in use by the RMS software. This problem has been fixed in version 1.3.0203 or higher.
If you are running on an older verison and don't have access to updates (active maintenance plan) we suggest you avoid grabbing the bar and instead click above or below the bar to navigate the report. Page Up/Down works too. If you have a long report and want to jump to a section of that report, place the cursor above or below the scroll bar where you want to jump, then right-click and select Scroll Here. You can use PageUp/Down from that position if you jumped too far.
F5/Refresh will also remove the black areas of the screen if they appear while scrolling. While F5 causes the report to regenerate, in most cases you will be returned to the same page position.
So if you do click the scroll bar and black areas begin to appear on the report, press F5 to restore the report view. Then continue using the procedure above.