A month or two ago I posted a message on this board concerning problems I was having with my XPS 435MT system. In a nutshell, every few weeks, it would either (a) temporarily fail to boot, and would restart several times before Windows fully loaded; or (b) randomly reboot while Windows was running. When either of these things happened, Windows would load successfully after a few attempts as if nothing had happened, but I would get a message stating that "previous attempts at booting this system had failed at checkpoint [D4]."
I called Dell and the rep I spoke with ran the usual diagnostics. Nothing was wrong with the RAM, motherboard, etc. She told me that the error message I had seen could be indicative of a problem with the hard drive, but I ran diagnostics on the hard drive and did not see anything wrong. I didn't have the time to continue the call after about 90 minutes, but was told to call back if I had recurring issues.
After speaking to the tech, I disconnected a USB external hard drive from my system, which had been giving me random problems for about a month prior. That seemed to fix the issue.
However, a couple of weeks ago, the booting problem returned, although I was not able to see the error message before Windows loaded. Then, the day before yesterday, the computer rebooted while I was typing an e-mail message. By the time Windows loaded normally, I was able to spot the error code--different this time: "Previous attempts at booting this system have failed at checkpoint [D2]." True to form, the issue hasn't resurfaced since.
I plan to call Dell tomorrow morning to troubleshoot more, but I wanted to see in the meantime if anyone knew what a "checkpoint [D2]" error is indicative of.