A small black rectangle appears in place of my minimize/close buttons and prevents these functions.
The small black rectangle is just large enough to cover the minimize/resize and close buttons in the upper right corner of the screen. It appears after I have been using the browser for a while. In other words, it is not there when I first launch Firefox. I am able to close the window by using the task manager but not by clicking where the black rectangle is. Sometimes when I click all through the black triangle, it resizes the window somewhat but not consistently.
Opaite Mbohovái (1)
Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).
- Don't make any changes on the Safe mode start window.
- https://support.mozilla.com/kb/Safe+Mode
In Firefox 4 and later Safe mode disables extensions and disables hardware acceleration. Try to disable hardware acceleration.
- Tools > Options > Advanced > General > Browsing: "Use hardware acceleration when available"
If disabling hardware acceleration works then check if there is an update available for your graphics display driver.