I tried to post this in the thread that comes up first in Google for the error message:
But it appears to be locked. So here I am. Please hear me out.
I encountered this problem, and was mystified - I'm a power user, I know how these things work, and there was no firefox.exe in the process list. I logged out, logged back in, just to make sure, and it *still* wouldn't work. So, out of desperation, I rebooted, and Vista gave me the "There are other people logged in and rebooting may possibly screw them over" message. Then it clicked - the other user probably had Firefox running, and that was probably what my Firefox Portable was detecting.
So upon reboot, I did some testing, and that was indeed the case. I logged in as myself, and then logged in as another user (Administrator), started Firefox from the local machine, and switched back to my login. Sure enough, I tried to start Firefox Portable, and it gave me the error.
When I brought up Task Manager, firefox.exe didn't show because it was under another user, and by default, Task Manager doesn't show other users' processes. I'm an admin on this machine/domain, so I don't know what privileges non-admins have, but I was able to check the "Show processes from all users" box* and kill the firefox.exe instance in the other session. I'm assuming non-admins don't have the privilege to kill, and perhaps even view, other users' processes, but I can't easily test that.
So what should be done? The easiest solution would be to add an addendum to the above-linked thread with a summary of this issue, so that people like me will Google it and find the solution.
A better, slightly more difficult solution would be to modify the error message in Portable Firefox so that it says something like "You or someone else logged into your machine has a copy of Firefox running. Rebooting will solve this issue, but may cause other users to lose work."
And even cooler, but probably not worth it for the minor issue that this is, would be to have Firefox Portable check to see what user is running the copy of firefox.exe and act accordingly - I'm not sure what that would look like, as I don't know if running two copies on different logins is any safer than on the same login.
*Note - another thing I noticed is that the Administrator login (but _not_ logins that just have admin privileges) have this box checked by default.
Quite a find!
I not sure how many people use switch user and would be effected by this [I try to avoid doing it at all costs] or if it's even been tested for use during a switch user environment but the question is a legitimate one. I'm sure John will chime in with some feed back on this.
Again, good find though.
You get todays investigative geek prize
Things have got to get better, they can't get worse, or can they?
This is actually a known issue and was first reported over a year ago, I believe. We don't have it mentioned on our known issues page, though as it doesn't come up much Most folks never use fast user switching.
This 'fast user switching issue' affects a good chunk of software programs including several popular apps. iTunes doesn't do fast user switching, for example. Windows doesn't fully isolate one user from another, so it causes issues.
We could do this with Firefox if we were using the local copy (you can run two instances of the same Firefox install under different users) but that wouldn't work as we'd lose portability, be using an unknown Firefox version, etc. The other way would be to use the multiple instances option but that presents us with other issues like tracking whether 'our' copy of Firefox has closed or not.
As Firefox gets more popular, it's become more of an issue, but for now, it will simply remain as it is. We should probably come up with a way to determin which user is running firefox.exe, though.
Sometimes, the impossible can become possible, if you're awesome!
I don't normally use fast user switching, but my coworkers do (hence the problem). I'm fine with it now that I know what the problem is - I just wanted to make sure that others were also aware of the problem, because it can be rather aggravating when it does happen, to have Portable Firefox insisting that you're running another copy of Firefox when you aren't, and Task Manager even says so.
As Vista gets more popular, I see this being more of an issue. I would advocate simply changing/updating the language in the error box - in iTunes' case, they make it clear that another user has iTunes open, I think something similar would be helpful. Modifying it to start "You or another user are already running an instance of Firefox..." would give a hint that someone else logged on might be the problem.
But in any case, it's not a huge issue, I mostly wanted to post so that others would be able to find it, since the other threads that come up in search don't mention it:
In addition, I searched on the error message and went through page 5 without finding any mention of the multiple issue - the thread must be quite buried, and therefore not very helpful for anyone with the issue.
And John, I know you do all this on your own time and are busy and such, so I'm not trying to demand or be whiny or anything - I'm very grateful for all the work you put into this, I use my PortableApps daily. So more than anything, thanks for all the work you put into this project!
I've got Portable...
Firefox, Gaim, GIMP, AbiWord, VLC, 7zip, OpenOffice, FileZilla, KompoZer.
Also: WinFrotz, FCEUltra, DOSBox, FSCapture, XVI32, Notepad++