Firefox is far more stable and secure than Internet Explorer. And it seems to have cured the login problem for a lot of people. You don't need to completely get rid of IE, or switch for everything (in fact I recommend keeping IE around for the few sites that aren't Firefox-compatible), but try it for the Combine and see if it works, and if you like it.
"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
In this case, the problem is often related to FF and IE storing passwords differently. For some reason this tends to stop working for players using IE to log into SWC. This is why we recommend it, since Firefox is a browser we know stores passwords in a manner that is more compatible. (:
If you have exhausted all of the suggestions in the sticky post, an admin will need to manually reset your password. Usually Khan does this but he has been busy lately. If no admins respond to your post I would recommend e-mailing firstname.lastname@example.org directly.