Hello HomerJ,
Every time that I have experienced this issue it is when something displaying on the screen has been causing the issue due to some corruption or error in the entities being displayed. For instance I have seen a corrupted defect and one that had extended information within a comment field that was causing the error when those items were displayed on the screen (or trying to be). What we had to do to rectify the issue was to remove the excess data and restart the client and continue to test until we had removed the offending information causing the display issue.

First I would check that the display zoom was at either 100% or 125%, as values outside of that range can cause the errors as well.