Licence error

Hi,

we had the following error on one of our company's computer last week :

"A problem is preventing Windows from accurately checking the license for this computer. Error code: 0x80090019"

When we click the OK button, we go back to the login screen.

In addition, while we're on front of the login screen :

- the USB keyboard and mouse can't be recognized (even if it's recognized in BIOS or in a WinPE environment). Usually it's recognized after waiting 1 or 2 minutes, it's the time for the USB driver to be loaded.

- another error message appears in login screen before entering the user session : "SQL Writer : SQL Dumper library failed initialization".

- if I start the user or admin session in Safe Mode, and try to do a right-click on My Computer, the contextual menu doesn't appear. Instead I got an error message saying "VpShellRes.dll could not be found" (that seems to be a Symantec Endpoint Protection DLL). Peoples reporting this error say it happens after uninstalling this Symantec software but we haven't uninstalled anything.

I've checked the solution purposed by Microsoft at http://support.microsoft.com/kb/914232 but WinTools is not installed on our computers.

The computer is a DELL Optiplex 760. The Windows licence has been provided by Dell so I think that the problem is not related to Genuine Validation, and the error messages are usually not this ones when there's a problem with licence validation. So any suggestion would be very welcome.

Thanks in advance.