Windows XP not allowing me to log in

So, here's the deal. I was installing a couple of programs on my computer last night to take an online class. No problem there, but when I went to restart the computer it got all the way past the windows loading screen to the blue screen where it has a windows icon in the middle of the screen and nothing else. The log in icons where I would usually click, and provide a password or not, is completely gone! I'm not sure what happened but apparently I'm stuck there. And I've read past forums about similar situations but everyone seems to say load this program or download this or that but how do you do that if you can't get into your computer properly even with safe mode. I tried to boot in safemode but I'm still not able to access my desktop or even get into windows period it just has the same blue screen but in a smaller box and with a black background. What exactly happened here? But more importantly how do I fix this and get into windows?

Thanking you all ahead for your advice and help through this matter,

Kommidus