If you don't want to clear all your cookies for some reason you can try just deleting the ones from ECF. Not sure which browser you're using, but in Firefox just go to Options and the Privacy tab and click on "show cookies". Here you can delete individual ones if you so choose. The steps should be similar in other browsers if you're not in FF
Also, if you use your browser's remember password feature then perhaps you need to update that entry. You can check if what's saved is correct and delete it if it's not (in Firefox it's in the Security tab in the Options menu)
Hope that helps
The reason I don't want to delete all my cookies is because I'd have to type my username and password in the biz-zillion websites that I've been to and I don't remember them all, not even a fraction of them but I did find the ECF cookies so if I have this problem again I will delete those. I'm using Google Chrome and I didn't know there was a search option for finding specific cookies so thanks for that.