Flock doesn't close properly

Very often, when I close flock, it stays in memory. Then if I want to launch it again, it gives me an error dialog saying that flock is still running and need to be closed first. We have then to kill the process using the task manager. Which is very annoying since flock is my default browser and opens every times I click on a link (this bug occurs at least ten times a day, I have to be in love with this browser to keep using it :).

I have a lot of extension installed, it may be the source of the problem, but I need those extensions for I am a web developer and I need flock as well to be my debug tool. If you say that plugins are a feature, then you cannot answer to this bug just saying "disable your extension". Fix this so extensions are properly closed (even if they have leaks) when flock closes.

Btw, I have the same problem with an instance of firefox on another box. It looks like it's a family problem :)

I'm using flock on Vista.