here (below) is one similar case, i hope.
i haven't read everything, just search the web and found this one with the word [RESOLVED], this might help you out.
[RESOLVED] Desktop is GONE - Tech Support Forum
that probably don't work for you.
so also try this, creating a new user account and then log off existing user and log into Windows with the new account.
may be the existing user profile is damaged or something.
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to open the Run dialog box - Windows logo key +R
to open Windows Task Manager - Ctrl+Shift+Esc
to open Control Panel type control
to open User Accounts applet type control userpasswords2
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Q9300 @ 500FSB
Q9300 @ 3.60GHz
4x1GB DDR2-1333 (PC2-10666)
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Don't worry overly much about whether a specific KB article exists for your version of Windows.
Standard practice is to grab whatever's available and apply the principles.
(I grabbed from the web. Written by someone, somewhere on the web)