Vista Ultimate 64-bit problem with remembering network passwords

My Vista Ultimate 64-bit is not part of a domain. Here are the steps
I'm having trouble with:

1. When I try to access our company SharePoint site via IE7 I'm asked
for the username and password. I key in DOMAIN\Username and the
password and check "Remember my password." I'm able to access the
site.

2. When I close IE, reopen it, and browse back to the same SharePoint
site and page I'm asked for the username and password again. This
time the username is pre-filled for me correctly, but the password is
blank. I can fill it in an access the site again.

3. Repeat back to step 2.

I would expect that after asking Vista to remember the password, the
next time I connect to the same resource it would at least pre-fill
the password, or perhaps even skip the login dialog box completely.

I'm having this exact same problem (having to retype my network
password every time) with:
- Outlook 2007 connecting to the company Exchange Server.
- Opening Office documents from the SharePoint site.

IE7 does do regular HTTP username/password remembering correctly.

I've also tried working with the "Stored User Names and Passwords"
dialog box. When I tell it to remember the password an entry is
created there, and I've tried re-entering my password directly there,
but still the problem remains.

I tried to live with it for quite a while, but when you're checking
email and working with multiple Office documents on multiple
SharePoint sites it gets a little ridiculous to be retyping my
passwords dozens of times per day.

Any help is very much appreciated. Sincerely,
Jason

It's not unique to Vista 64 - same behavior with virtually every system I've
encountered recently with SharePoint.