Firefox won't run suddenly nor uninstall


New Member
Well, everything was hunky dory for a while, but now, firefox won't start because it says another instance of it has to close first, but there is no other instance.

On top of that, I can't run it in safe mode because I get the same error.

On top of THAT I can't uninstal it, when I try to uninstall, nothing happens at all, after clicking on uninstal.

What can I do?


Windows Forum Admin
Staff member
Premium Supporter
I have a copy and was running beta 2, but I am not currently testing it right now and its not installed. I wish I could test this for you and find a solution. I found Vista to be a bit too demanding for my system in its current state, and I was reluctant to start using it as my "main OS" especially given the year expirey and thats in beta - I won't have access to more stable builds.

I would say just hold out for now and don't run Firefox. Maybe someone from Mozilla can help you, there are alot of support newsgroups. If someone actually from MSDN comes by maybe they might know whats causing this. I did try to search for a solution for you amid fixing some problems on the website.


New Member
Alright hrm first off check and see if there is an errant firefox.exe running in the processes list. This is almost the same process as checking/ending a process in Windows XP. Instead of using task manager (I assume you tried to see if firefox.exe was running there) we're going to use the new and improved PowerShell (formerly Monad). Yay we get to use our amazingly superpowerful command-line scripting system. A shame it's such a small task..
Simply open PowerShell and input the following command:

Stop-Process –processname firefox

Get-Process firefox | Stop-Process
Please note two things from my examples.
Firstly notice the distinct lack of a .exe extension, that is because of the way that PowerShell stores ProcessName strings.
> Get-Process notepad
Handles  NPM(K)    PM(K)      WS(K) VM(M)   CPU(s)     Id ProcessName
-------  ------    -----      ----- -----   ------     -- -----------
     65       2     1628       1836    15     0.03   2024 wdfmgr
    557      65     8184       3824    57     1.06   1220 winlogon
    569      26    48748      77912   542   282.86   3116 WINWORD
    149       4     2024       5288    37     0.17    808 wmiprvse
     48       2      916       3404    29     0.06   2820 WZQKPICK
Secondly note that my second example listed here, using the "Get-Process" midlet and piping it through to Stop-Process, will in fact only kill the first process named "firefox" not all of them, so if you want to kill all instances I recommend using my first example.

Firefox appdata is stored in F:\Users\[UserName]\AppData in Vista.. so you could check here and remove your profile information in case it's corrupted, then try running Firefox
hope this was useful to you. For some more PowerShell information check out my post on how to add command history support to PowerShell here.