I have an adwords account and have tried using this login as instructed, or creating a new login. All I get is that the email field should not be left blank.. which it never is.
I have emailed google.. and recieved two replies taking nearly a month, both had little to do with my request for help and read like automatic or at least genric posts. Both explaining how to solve problems with the adsense account I don't have :)
Anyone got any suggestions apart from keep promoting my site until espotting will take it :)
Have you tried closing your browsers and starting a new browser session? Sometimes that will fix login problems. Are your cookies enabled? Have you tried using a different browser - if you use IE try Mozilla? Or even using a friend's computer just to apply? It sounds more like it is a tech issue with your computer, than a problem with AdSense. If you have had this problem for a month, I am sure we would have had at least a few irate potential publishers posting about it here.
Someone else might have some other ideas, but these are the first things I thought of off the top of my head.
I received a different error ("There is a problem with your account" or something generic like that) and I found that when I used different e-mail addresses for AdSense and AdWords accounts, things went fine.
A note to Google about the issue resulted in a prompt but relatively unhelpful reply, basically along the lines of "Our engineers are aware of potential problems in this area; please signup using a different e-mail address in the meantime."