I am not entirely sure on what this means :
move the new MBR.dat file to a form of removable storage media as a precaution.
And this is the MBR log :
aswMBR version 0.9.4 Copyright(c) 2011 AVAST Software
Run date: 2011-04-07 16:16:38
-----------------------------
16:16:38.993 OS Version: Windows 6.0.6002 Service Pack 2
16:16:38.993 Number of processors: 2 586 0xF06
16:16:38.994 ComputerName: THOMAS-PC UserName: Thomas
16:16:40.994 Initialize success
16:16:42.732 Disk 0 (boot) \Device\Harddisk0\DR0 -> \Device\00000032
16:16:42.734 Disk 0 Vendor: SAMSUNG_ 1AJ1 Size: 476940MB BusType: 3
16:16:42.735 Device \Device\0000005f -> \??\SCSI#Disk&Ven_SAMSUNG&Prod_HD502HJ#4&358dcf36&0&000000#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} not found
16:16:42.737 Disk 0 MBR read error
16:16:42.739 Disk 0 MBR scan
16:16:42.741 MBR BIOS signature not found 0
16:16:42.743 Disk 0 scanning sectors +976771072
16:16:42.746 Disk 0 scanning C:\Windows\system32\drivers
16:16:46.896 Service scanning
16:16:48.017 Disk 0 trace - called modules:
16:16:48.040 ntkrnlpa.exe CLASSPNP.SYS disk.sys acpi.sys hal.dll >>UNKNOWN [0x852d7ecc]<<
16:16:48.043 1 nt!IofCallDriver -> \Device\Harddisk0\DR0[0x86167a30]
16:16:48.046 3 CLASSPNP.SYS[82fab8b3] -> nt!IofCallDriver -> [0x85260520]
16:16:48.049 5 acpi.sys[806996bc] -> nt!IofCallDriver -> [0x8528bc90]
16:16:48.054 [0x8683caf8] -> IRP_MJ_CREATE -> 0x852d7ecc
16:16:48.058 Scan finished successfully
aswMBR version 0.9.4 Copyright(c) 2011 AVAST Software
Run date: 2011-04-07 23:00:05
-----------------------------
23:00:05.819 OS Version: Windows 6.0.6002 Service Pack 2
23:00:05.819 Number of processors: 2 586 0xF06
23:00:05.820 ComputerName: THOMAS-PC UserName: Thomas
23:00:07.465 Initialize success
23:00:08.741 Disk 0 (boot) \Device\Harddisk0\DR0 -> \Device\00000032
23:00:08.743 Disk 0 Vendor: SAMSUNG_ 1AJ1 Size: 476940MB BusType: 3
23:00:08.745 Device \Device\0000005f -> \??\SCSI#Disk&Ven_SAMSUNG&Prod_HD502HJ#4&358dcf36&0&000000#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} not found
23:00:08.747 Disk 0 MBR read error
23:00:08.749 Disk 0 MBR scan
23:00:08.751 MBR BIOS signature not found 0
23:00:08.753 Disk 0 scanning sectors +976771072
23:00:08.756 Disk 0 scanning C:\Windows\system32\drivers
23:00:12.738 Service scanning
23:00:13.808 Disk 0 trace - called modules:
23:00:13.825 ntkrnlpa.exe CLASSPNP.SYS disk.sys acpi.sys hal.dll >>UNKNOWN [0x852d7ecc]<<
23:00:13.828 1 nt!IofCallDriver -> \Device\Harddisk0\DR0[0x861d8ac8]
23:00:13.831 3 CLASSPNP.SYS[82f9d8b3] -> nt!IofCallDriver -> [0x8488d700]
23:00:13.834 5 acpi.sys[8069b6bc] -> nt!IofCallDriver -> [0x85256c90]
23:00:13.838 [0x86c2cd88] -> IRP_MJ_CREATE -> 0x852d7ecc
23:00:13.841 Scan finished successfully
23:00:15.268 Disk 0 MBR fix error
23:00:17.740 Disk 0 MBR fix error
23:00:18.228 Disk 0 MBR fix error
23:00:18.748 Disk 0 MBR fix error
23:00:18.956 Disk 0 MBR fix error
23:00:19.148 Disk 0 MBR fix error
23:00:19.356 Disk 0 MBR fix error
23:00:19.540 Disk 0 MBR fix error
23:00:19.748 Disk 0 MBR fix error
23:00:20.116 Disk 0 MBR fix error
23:00:20.348 Disk 0 MBR fix error
23:00:20.604 Disk 0 MBR fix error
23:00:20.860 Disk 0 MBR fix error
23:00:21.148 Disk 0 MBR fix error
23:00:21.436 Disk 0 MBR fix error
aswMBR version 0.9.4 Copyright(c) 2011 AVAST Software
Run date: 2011-04-07 23:01:03
-----------------------------
23:01:03.862 OS Version: Windows 6.0.6002 Service Pack 2
23:01:03.862 Number of processors: 2 586 0xF06
23:01:03.862 ComputerName: THOMAS-PC UserName: Thomas
23:01:05.588 Initialize success
23:01:06.438 Disk 0 (boot) \Device\Harddisk0\DR0 -> \Device\00000032
23:01:06.441 Disk 0 Vendor: SAMSUNG_ 1AJ1 Size: 476940MB BusType: 3
23:01:06.442 Device \Device\0000005f -> \??\SCSI#Disk&Ven_SAMSUNG&Prod_HD502HJ#4&358dcf36&0&000000#{53f56307-b6bf-11d0-94f2-00a0c91efb8b} not found
23:01:06.444 Disk 0 MBR read error
23:01:06.446 Disk 0 MBR scan
23:01:06.449 MBR BIOS signature not found 0
23:01:06.451 Disk 0 scanning sectors +976771072
23:01:06.454 Disk 0 scanning C:\Windows\system32\drivers
23:01:10.348 Service scanning
23:01:11.497 Disk 0 trace - called modules:
23:01:11.517 ntkrnlpa.exe CLASSPNP.SYS disk.sys acpi.sys hal.dll >>UNKNOWN [0x852d7ecc]<<
23:01:11.520 1 nt!IofCallDriver -> \Device\Harddisk0\DR0[0x861d8ac8]
23:01:11.523 3 CLASSPNP.SYS[82f9d8b3] -> nt!IofCallDriver -> [0x8488d700]
23:01:11.526 5 acpi.sys[8069b6bc] -> nt!IofCallDriver -> [0x85256c90]
23:01:11.530 [0x86c2cd88] -> IRP_MJ_CREATE -> 0x852d7ecc
23:01:11.533 Scan finished successfully
23:01:12.884 Disk 0 MBR fix error