sdclt.exe is the process for the Vista backup tool. It's also present in Windows 7 and probably 8.
It should not prevent you from login into your computer.
You should read this article from Microsoft:
http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/sdcltexe-missing-and-backup-and-restore-stop/a9360370-a050-4bbf-b981-414673d669bb
From the information here: http://windowshelp.net/windows-processes/sdclt.exe.aspx
It's not a critical process, but is needed to perform backups and restoring those.
There are instances of malwares masquarading under that file name, but they usualy reside outside of the \Windows\system32\ folder, but it's not impossible for some to actualy replace the legitimate file with a malicious one.
Use some anti-virus to scan your computer and correct the problem if you have an infection.
Electro, October 2013
