Try killing Firefox with the Windows Task Manager. It should then restart without you needing to create a new profile. * [["Firefox is already running but is not responding" error message - How to fix it]] Firefox should not do that repeatedly. Unfortunately there are a lot of potential causes of such hangs please look through this article which describes causes and possible solutions * [[Firefox hangs or is not responding - How to fix]] After reading that please say what you have tried, and whether anything seems to help. Additionally whilst you have problems I would suggest you give Firefox at least ten minutes to shut down, or if you still see disk activity give it longer; before trying to power down the computer or somehow kill Firefox. Note Firefox should time-out if it takes too long to shutdown. Firefox will then take even longer as it will try to generate and submit a crash report. Are you seeing CrashIDs from Crash reports ? * See [[Mozilla Crash Reporter]] Also note if it has problems at shutdown that can have a knock-on effect and cause slow startups as it tries to tidy up.