I had this problem for 5-6 months, was getting some other errors, but this was most common, I ran MEMTEST and got like 20K errors, couldn't boot every time, would crash often, after starting PC like 20X it would finally run, but not always for more than 4-5 hours, sometimes a week.
I had tried 2 different sets of memory, different video cards, different hard drive, reinstalled windows.
After all that, it ended up being my motherboard, sent it in for RMA, they replaced it and I put it in my PC, voila! success! I don't know what you're running, but i have a asus 785td-m Evo
Stop 0x000000D1 or DRIVER_IRQL_NOT_LESS_OR_EQUAL
The Stop 0xD1 message indicates that the system attempted to access pageable memory using a kernel process IRQL that was too high. Drivers that have used improper addresses typically cause this error.
Interpreting the Message
This Stop message has four parameters:
IRQL at time of reference.
Type of access (0x00000000 = read operation, 0x00000001 = write operation).
Address that referenced memory.
Resolving the Problem
For additional troubleshooting suggestions that apply to all Stop errors, see "Stop Message Checklist" later in this appendix.
Stop 0xD1 messages can occur after installing faulty drivers or system services. If a driver is listed by name, disable, remove, or roll back that driver to confirm that this resolves the error. If so, contact the manufacturer about a possible update. Using updated software is especially important for backup programs, multimedia applications, antivirus scanners, DVD playback, and CD mastering tools.
For more information about Stop 0xD1 messages, see the Microsoft Knowledge Base link on the Web Resources page at http://www.microsoft.com/windows/reskits/webresources. Search using keywords winnt, 0x000000D1, and 0xD1.
Ok so apparently its not the RAM, a reinstall doesn't work, its surely not the motherboard as it boots into BIOS fine. I'm so confused it was working fine when I had it
my MB booted to BIOS quite often, would typically crash after BIOS,, wasn't till it got really bad before it had hard time with BIOS as well. if you change the memory and the problem still there and reinstall windows to reset all drivers and problem still there, and update all drivers and problem still there,,,, I would say it is the motherboard, mine was only a few months old when problems started and took a loooong time for me to figure out as everyone and their dog said it HAD to be memory - I tried different timings, slots, sticks, stick sizes, 1 to 4 sticks, nothing worked 000 it was the MB.