Help requested

I have whined here about my computer woes, which only grow worse. So a clarion call to all readers who might help. But, first, some specifics...

My workstation is a Dell XPS 420, new and installed since 6 months ago. It comes fully tricked out with 4Gb of RAM, its nVidia video card has the most up-to-date drivers... and, unfortunately, Windows Vista SP1. (I believe the source of all the computer's problems is the OS, but just in case...) What occurs now, and increasingly so, is that, while in the middle of some task, the monitor goes black. The CPU, though, continues to work, I just cannot see what is on the screen. (Sometimes I can see and move the cursor, which is the sole item I can see when this event occurs.) This problem has been described to me as a "system crash" -- where the OS (Vista) cannot 'communicate' with one component or another. In the attempt to isolate the cause, I thought the problem might have been Yahoo Mail (which frequently crashes the browser iterations), but no, not Yahoo Mail; I then thought it was iTunes, but no to that possibility as well.

I am tired of losing productive time, just as I tire of shutting down the computer the 'bad' way -- via depressing its 'on' button for 5 seconds -- but I have no other option. (Dell does not provide its computers with an emergency shutdown switch.) Sooner or later, these shutdowns will corrupt the hard drive... and then what?

So, my questions: How can I discover the cause of this problem? And, more important, what can I do to fix it?

And, yes, sooner or later -- most likely sooner -- I will migrate to Apple. For now, though, I appreciate any specific help, guidance, or pointers you might offer. Share them here as a comment reply, or email them to mailto:davidmgordon@gmail.com.

Thank you.
-- David M Gordon / The Deipnosophist