Try this on an affected computer. This worked for me:
There are passwords that can be stored in the SYSTEM context that can't be seen in the normal Credential Manager view.
Download PsExec.exe from http://technet.microsoft.com/en-us/sysinternals/bb897553.aspx and copy it to C:\Windows\System32 .
From a command prompt run: psexec -i -s -d cmd.exe
From the new DOS window run: rundll32 keymgr.dll,KRShowKeyMgr
Remove any items that appear in the list of Stored User Names and Passwords. Restart the computer.
also, there are scripts that you can run (i did not test, found them on stack exchange) to do this if they are run as system user:
Script one:
cmdkey.exe /list > "%TEMP%\List.txt"
findstr.exe Target "%TEMP%\List.txt" > "%TEMP%\tokensonly.txt"
FOR /F "tokens=1,2 delims= " %%G IN (%TEMP%\tokensonly.txt) DO cmdkey.exe /delete:%%H
del "%TEMP%\List.txt" /s /f /q
del "%TEMP%\tokensonly.txt" /s /f /q
Script 2
for /F "tokens=1,2 delims= " %G in ('cmdkey /list ^| findstr Target') do cmdkey /delete %H
I hope this helps. I found this solution for something completely unrelated, and it resolved this months old problem for me :)
