"Windows Logon UI" was the error code after installing 4/4/07 upda

I have Windows XP with Service Pack 2 installed. On 4/4/2007 my update
installer was flashing, so I installed it like I usually do, it needed a
restart. so I restarted it and when it got to the welcome screen I chose my
name and a Windows Password Logon Window appeared. (I have never used a
password to get on the computer and now it wants one.) I clicked "ok" and it
went to my desktop, but it had no Icons, no Taskbar, the mouse moved around
with no purpose. I decided to shut the computer down, The Microsoft Error
Box so you can send the information back to Mircosoft to evaluate it, it said
Windows Logon UI, the Error Report Contents list the following:
C\Docum 1\Owner\Locals \Temp\Wer9c82.dir000\Logonui.exe md mp
C\Docum 1\Owner\Locals \Temp\Wer9c82.dir000\AppCompat.txt
I sure hope someone can help or I will have to start all over.
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arcticat