Addressing E-mails Enhancement Request

When addressing e-mails, I see the following when I type in the e-mail address:

As I type in the e-mail address, the address beings to scroll after typing just a few characters, even though there's plenty of room in that address field.

Then when I press the comma or semicolon key to being entering in another e-mail address, it duplicates the e-mail address I just entered.

I can of course enter in the address even if I can only see a few characters at a time, and I can hit the delete key a few times to get rid of the duplicate address, but it's annoying and not something that should be there.

The premature scrolling for the address occurs using both Safari and Firefox on a Mac running OS X 10.6.4 and on an iPad. The duplicate address doesn't occur using Firefox, but does using Safari or the iPad. I haven't tried this with any other computers.