Your first minidump is an 0xA error and these are strong indications of hardware issue. In your case it cited memory. As good as Memtest is it is not uncommon for bad RAM to pass the test. I suggest running the test on each stick for a minimum of 7 passes.
The other two errors are 0x50: PAGE_FAULT_IN_NONPAGED_AREA
Requested data was not in memory. An invalid system memory address was referenced. Defective memory (including main memory, L2 RAM cache, video RAM) or incompatible software (including remote control and antivirus software) might cause this Stop message, as may other hardware problems (e.g., incorrect SCSI termination or a flawed PCI card).
What firewall and antivirus do you run?