Occasionally when I start up my computer and try to launch Thunderbird I get this error ...

"Thunderbird is already running, but is not responding. To open a new window, you must first close the existing Thunderbird process, or restart your system."

Thunderbird is definitely not running, nor is there a process to close. If I restart my PC and try again it normally launches okay.

Any help appreciated.

Jo, June 2007

I get the same message for Firefox and several other programs. I open Task Manager and go to the tab that says processes. I find that there are several instances of Firefox running in the background and I cause them to close with Task Manager. Then I open one instance and that solves the problem. Haven't figured out yet how I get more than one instance of Firefox or other programs running

thegaffer, July 2008

If you have your profile in a shared folder on a network drive and launch Thunderbird immediately after starting your PC, you may need to open Explorer to make a connection to the shared folder before you launch Thunderbird.

So, if you see this error, close the Thunderbird error message, open Explorer and navigate to the drive which contains the shared folder, then try launching Thunderbird again. This works for me. It seems that Thunderbird can't start the first connection to a shared folder on a network drive.

Tim Winch, November 2007