This is actually a problem and what I did to fix it.... Firefox 25 and Mac OS 10.7 (Lion) Went to "Clear Recent History" and Firefox stopped responding. • I had to use COMMAND-OPTION-ESC to quit Firefox I then went to Firefox preferences-->Privacy-->History • I changed "Remember History" to "Use custom setting for history" • I checked the box that said, "Clear history when Firefox closes" THIS IS WHEN THE PROBLEM HAPPENED • Clicking Firefox from my Startup Menu would cause the pointer to spin endlessly • Again, I had to use COMMAND-OPTION-ESC to quit Firefox At this point I was worried that I could lose all of my Bookmarks with a clean install, so I went to the internet and found out I could start Firefox in a "Safe Mode" Here is what I did to correct the problem.... 1) Hold down option and click Firefox from the Startup Menu (Firefox starts in Safe Mode) 2) I then went to Firefox preferences-->Privacy-->History 3) I unchecked the box that said, "Clear history when Firefox closes" 4) I changed "Use custom setting for history" to "Remember History" 5) I closed the Firefox preferences and Quit Firefox When I restarted the computer all of my Bookmarks had returned :-)