Two problems with Steam application

First thing to do when you have any problem with Steam, quit it, delete/rename the "ClientRegistery.blob" file in its folder, and relaunch it.

Usually solves about 90% of the problems.

delete everything from steam directory except "steamapps" folder and steam.exe, open steam.exe it will download everything again but not the games (they are saved in steamapps)
make sure there is no read-only files

and make sure the box in steam settings "don't save credentials on this computer" is unchecked

if this doesn't solve, try looking for anything like antivirus or another programms, or anything else making the steam client don't save the settings on your computer, like limited account isssues and that

Start steam as admin, so the client can save your settings. Start it normal next time and everything should work (source: had the same problem a year ago)

I Have another problems, Can anyone help me?
1- Can't get rid of this "1 item is downloading" notification.
2- Steam can't download a single byte of TF2 last update for 2 weeks.

I have to add that I am actuallly using Steam Beta, I have reinstalled Steam some time ago to another location (that was time when the issue started happening).

Steam client does accept user/password as params, so you can add them to your windows shortcut.
I can not lookup the syntax right now. if I get home and remember this post, I will update it, or you could simply use google in the meantime.
But I don't know if the beta accepts the same params.