Blank Desktop After Windows XP Login on Network

After restarting Windows, signing onto the network at the login screen, my desktop shows old wallpaper I use to use and absolutely nothing else except the cursor. I've tried running malwarebyte, Trend Micro, Spyware Doctor, Super Anti Spyware and Symantec with no success. I've also been able to CTRL+ALT+DEL to bring up Task Manager and typed in "explorer" and "explorer.exe" and get the message: "Windows cannot find 'explorer'. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search." I've also typed in "regedit" and went to HKEY_LOCAL_MACHINE, SOFTWARE, Microsoft, Windows NT, CurrentVersion, Winlogon, Shell...and made sure that the only thing listed was 'Explorer.exe'.

I don't know what else to try, I'm out of options and I need my computer back...please help!

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