Not a question - more of an FYI. The other day I went to start my computer and started freaking out as every time it booted It would say "Operating System not found". Nothing scarier than those four words...it's just short of saying "you just lost everything - tough luck"... Fortunately I'm a computer guy so I didn't overly panic. I have an external hard drive case I slapped the hard drive into and found that the files were still there...A good sign..at least I knew I could get my files. Then I reinstalled the hard drive, and went through the repair feature....It worked! Must have been a corrupt boot up file.... Nothing exciting about the repair but before I did the repair I attempted to look up the symptoms on line...and didn't find a similar problem. Hoping in the future no one panics and wipes out their hard drive as a drastic measure to missing operating system. I did loss the Vista operating system. The repair feature did work. D

Google is your best friend http://support.microsoft.com/kb/321626

"I attempted to look up the symptoms on line...and didn't find a similar problem" Heh - that must've been quite the attempt, Mr 'computer guy' I'm not one of those who think Bill Gates is the devil. I simply suspect that if Microsoft ever met up with the devil, it wouldn't need an interpreter

Jboy That's what I said but in a more tactful way.

Cool!! But just a question how did you backup the files from your External HDD? Does your External HDD has Existing OS (XP or VISTA)? or you used WINRE on Vista? Because we had the same issue with a DELL C521, Tried running a repair but under the partition where Windows was installed it shows Capacity is 139gig and free space is 139gig which means likely there's no OS installed on that Partition. tried using XP CD, under window Setup is shows Unknown partition. That's why i'm wandering how did you backup your files? and just to add up on this issue. We manually install Vista, But problem still reoccured.. Hoping for your reply.. Thanks in advance

I have been having the same exact problem on a Dell C521. Ever since I installed Vista, it wouldn't boot once a week or so saying "missing operating system." I would boot with the Vista DVD and do a "Startup Repair" and it would fix the boot sector and away we'd go for another week or so. Finally after 2 months the "Startup Repair" wouldn't work saying that the MBR (Master Boot Record) was missing. Foolishly, I reinstalled Vista, which wiped my drive WITHOUT WARNING. XP never did that. Anyway, the Dell diagnostics show no problems, BIOS, hard drive, motherboard all come up clean, so Dell won't have anything to do with it since I didn't buy Vista from them (its Vista Business not retail if that matters). I reinstalled 5 days ago and haven't seen the problem again, but I will thoroughly test before I put my family back on, along with a very comprehensive backup system. Will also check for BIOS updates. Have you or anyone gotten any resolution here? Two C521 systems from Dell having the exact same problem does not seem like coincidence. Best of luck

Hey, I guess not only from two of you guys having the same problem. Me too. I just bought the Dell C521. I'm having the same issue. I post the problem on the Dell forum and other IT forum. They seems trying to help but still unsolved. I hope I really can use this computer without any problem and I'm first time to use Dell computer so I hope they dont dissapointed me.