Due to a build up of signature spam, we have had to reset all signatures that contained a URL. If your signature did not contain a URL then you should not be affected, but you might want to double check it. We will no longer be able to support bbcode URLs in signatures going forward, and we will keep an eye on this for abuse.
My apologies to anyone who is adversely affected by this. We did have a lot of legitimate signatures with URLs, however due to Google's new algorithm we were being adversely affected by link spam in our forums and had no choice.
If you spot a suspicious signature please let us know immediately.