As this is a fairly old bug with no recents reports or comments, and it seems to be fixed in System Monitor 3.3.4 on Precise, see the attached screenshot showing the result after following the steps to reproduce from the comments, I am marking this as Fix released.
Feel free to reopen this if you manage to reproduce this, and comment with the exact steps to reproduce the issue.
As this is a fairly old bug with no recents reports or comments, and it seems to be fixed in System Monitor 3.3.4 on Precise, see the attached screenshot showing the result after following the steps to reproduce from the comments, I am marking this as Fix released.
Feel free to reopen this if you manage to reproduce this, and comment with the exact steps to reproduce the issue.