I think there was an update recently for PSE7. Did you install the update recently. After this update the PS.com login would not work untill you upgrade to PSE 7.0.3.
Use this info to upgrade: http://kb2.adobe.com/cps/841/cpsid_84110.html
If you have already upgraded you PSE7, try login into browser on www.photoshop.com and see whether you are able to login or not.
That did not work. I went to the organizer / help / updates... and got a
message that says. The update server is not responding, which means it might
be offline at the moment, or the Internet or firewall settings may be
incorrect. Please try again later.
I tried going to product updates under photoshop elements for windows. Under
version 7.0, I clicked on Adobe photoshop elements 7.0.3 update 4/27/2010. I
went through that and it said that the product had been successfully
updated. I tried logging on again after restarting my computer but i
continue to get the same error.
I can't log into my account. Is there anything else you can suggest?
I am not sure if 7.0.3 is applied on your machine or not.
400 error comes when a bad request is made which could be dew to older version of PSe which is not yet updated...
As you mentioned Updater is also not working on your machine, Try the other method of downloading the update from Adobe.com and apply it. It should solve the problem.
By any chance, do you use any proxy?