I have an Alienware Aurora ALX, i7, 6G RAM, 460 GTX, A09 BIOS (originally), A11 BIOS presently.  The original problem was that my system would hang 90% of the time coming out of Sleep Mode, forcing me to hard power down the system.  In attempting to remedy this problem, amongst updating drivers etc., I came across the BIOS update on the Dell support site.  The BIOS flash apparently failed, as the system would no longer post.  See http://en.community.dell.com/owners-club/alienware/f/3746/t/19361225.aspx for a fairly apt description of the issue.  Although very reluctant, Tech Support did do what Chris M. suggested, and sent me a new MB, which brings us to the present issues.

As stated previously the new MB came with A11 BIOS.  The system now posts, however it is constantly hanging.  It hangs pre-post, it hangs mid-post, it hangs post-post.  It hangs while editing BIOS settings, it hangs before booting to windows, it hangs after booting to windows, it hangs while booting windows, it hangs while doing system diagnostics; there is no pattern. However, I left the system turned off overnight, I was able to boot it in the morning run in windows for about 45 minutes, downloaded a couple drivers, did a windows update, but after it was restarted it froze while booting into windows.  After a forced power down, it hung prior to getting to windows, and then in random locations as outlined above.

I was able to do several of the diagnostic tests yesterday, although a few of them were interrupted by a system hang.  But it made it all the way through the "Symptoms Tests" of system freezing.  The only one I was not able to complete was the video tests, the first screen showing the three triangles was as far as it would get.

I am out of warranty and completely flabbergasted.  I had previously owned an XPS 410, and never had anything outside the "normal" issues.  Any help would be greatly appreciated, as I am completely disenchanted with the entire situation.