John here, customer advocate at Dell headquarters.

The only thing I can think of is that something is interfering with the screen saver, perhaps a program or an input device malfunction. Is this the only symptom you're seeing?

I would first try to activate the screen saver after clean booting as described in the following article:

[url=http://support.microsoft.com/kb/331796]How to perform a clean boot procedure to prevent background programs from interfering with a game or a program that you currently use[/url]

If the screen saver kicks in there, you know that something you're filtering out in clean boot is the culprit. If that's the case, use method 3 as described in the article to fix the problem.

If you need any help, let me know:

[email]customer_advocate@dell.com[/email]
ATTN: John