passwords fail

hi, i have had this problem on and off for a couple of years as i rarely need it i havnt bothered doing anything about it, however it's puzzling and annoying me. this happens (sometimes) on avira, eset, txguitar, and 2 games forums (secure forums, ie you have to log in to see them) basically any site that requires the windows, center of screen pop up log in box.
it just flashes and reappears as though the wrong password has been entered on the third attempt i get a message stating 'this site cannot verify you, you have either entered an incorrect password or your browser is not capable of submitting this information'
i have all cookies enabled.
i have run ccleaner and manually deleted the cache.
this happens on ie7 (inc ie7pro), firefox and opera.
i dont use a firewall
avira premium av
and spyware blaster

i know this may not be a swb problem, i just wondered.

another thing, the eset site lets me download from the uk site, but any other sites fails. i contacted eset to find out why and the response was "your password works fine, i just tried it on two other sites without problem"
but it doesnt work for me?
(i no longer have eset installed just avira and spw)