Pros for you
- If your account is stolen, the other users won't be able to repeatedly login with your account.
Cons for you
- You have to do a one-time validation
Pros for Steam
- It is harder for people to share accounts, since only one e-mail can be listed and they will always get the notifications.
I know of only one way that this can happen in windows, and has nothing to do with Steam other than their not-so-great decision to install all content into Program Files.
If you are on Windows 7 or Windows Vista, and you have UAC set to ON, then change it later to OFF, this can happen.
UAC does thing evil thing where if a program tries to write to a "protected" area like Program Files, EVEN IF YOU ARE ADMINISTRATOR, when you get a UAC prompt and give permission, it actually writes any files that would normally go into that directory into a "virtualized" directory somewhere else.
If you turn off UAC, that will no longer happen, and as an awesome bonus, it will no longer know about the files that it virtualized.
So in your case, if you had UAC on, installed a ton of games, then later got sick of UAC and turned it off, this would happen as you described.
See the second paragraph in "Features" in the article on User Account Control.
If you have done this and turn on UAC again, your content will come back, but be a TOTAL mess because if you've downloaded more stuff with UAC off, then that will be invisible when you turn UAC on, and vice versa.
this drove me a little crazy once before I realized what was happening.
i'm curious to know if this is your issue.
Best Answer
Try to log in at steampowered.com so you can see whether it's a client or login data issue. Also make sure you don't use your community profile name instead of the username (they can be different, it took me a while to remember that after not having used steam for a while).
If you also cannot login there, follow theses instructions from steam, basically it means installing the client again (as you intended to do anyway) and selecting
I don't know my account name(it will be emailed to your registered address) orI know my account nameif you are certain about it (asking for the answer of the secret question).If this still fails, contact support.