can't login..black Windows screen

[HeatherO]

I completely lack computer skills!
 When I turn on my computer like I normally would, the screen comes up black in the background and it says "Microsoft Windows XP (with the logo)" and then under it, it says, "to begin, click username" There are no usernames to click on though and I cannot get past this in any way. There are no other available options.
By pressing ctrl+alt+delete I was able to get a place to login, but when I try, everything i put in says.."your username or password may be incorrect...blah blah."
 We have two "sides" to our computer, we log into our side w/ a password and our son logs into his w/out one. I tried his w/out password & ours with its typical password, but it never gets us anywhere! I have tried pressing F8 and many of the options given there, but with no luck! Does anyone have any advice for me? I would appreciate it SO much! I am on another computer now, but our main computer has everything on it!! Thank you!

[Carbon Dudeoxide]

You're talking about this screen, right?
http://www.raymond.cc/images/xp_welcome_screen.gif

What happened before the problem? (Downloads/installs/hardware changes/ect....?)

When did it start?

Can you log in via Safe Mode?

[HeatherO]

Yes..that is the screen, but instead of its usual color, it is black in the background, and it says to "log in", but there is nothing to click on in which to do so! I have tried clicking all around the screen, tried entering in "safe mode" (just takes me to the same screen, but safe mode "style" to log in...black background again, and nothing to "click" on)
I have also tried pressing F8 and doing "last known good configuration" which makes the computer seem like its doing something, but takes me again back to the "black" login screen with nothing to click on to login!
I also tried F8 and safe mode w/command prompt, all to no avail
I am not aware of any changes, downloads, etc. that have happened recently, and all computer "users" in my home have said they have not done anything out of the ordinary, so I am completely stumped & very frustrated & worried! I do not want to restore & lose all my valuable photos & computer "info"
I don't know if it is just something simple....or big trouble!
Would appreciate any input so much!
THANKS!