Set the crash dump to small memory dump. Create the Minidump folder manually. See if it creates a dump file next crash. Be sure pagefile is enabled. Also see this article. I doubt it applies to most users but is worth a look.
This article is for XP but the cause section applies to Vista and W7 also
The Memory.dmp file already exists and the option Overwrite Any Existing File (found in Control Panel System) is not selected. It is a good idea to leave this box checked and to move or copy the current Memory.dmp file.
The paging file on the boot drive is not large enough. To use the "Write Debugging Information To" feature to obtain a complete memory dump file, the paging file on the boot drive must be at least as large as physical memory + 1 MB. When you create a kernel memory dump file, the file is usually around one-third the size of the physical memory on the system. Of course, this quantity will vary, depending on your circumstances.
The paging file is not on the %systemroot% partition. When the STOP error occurs, the system crash dump is written out to the pagefile on the root of the %systemroot% drive.
There is not room for the Memory.dmp file in the path specified in Control Panel for writing the memory dump.
It is possible that the SCSI controller is bad or the system crash is caused by a bad SCSI controller board.
If you specify a non-existent path, a dump file will not be written. For example, if you specify the path as C:\Dumpfiles\Memory.dmp and no C:\Dumpfiles folder exists, a dump file will not be written.
As a last resort you can uncheck the "automatically restart" in the startup and recovery settings. This way you can at least see the bsod message and write it down. While you are in there Uncheck "overwrite any existing file"