Blue Screen 0x00000051

Hi Piyawat,

It seems parts of the registry that is used when you recover to an earlier state (last known good configuration) has become corrupted.
Since Windows keeps track of the last known good configuration, and attempts to save it everytime you boot but can't giving it's corrupted, it prevents your system from properly booting.

Unfortunately, with the age of a pc like yours, there are quite a few things that should be checked to find the root cause. The main parts that need to be checked are the RAM and HDD.
Not knowing your knowledge and experience in IT and whether or not any hardware has been replaced in those years, I want to warn you that you should not run any tests like chkdsk, SeaTools or similar tests on an old drive. The tests won't damage the drive, but they are very intensive tests and a drive that's giving signs of failure will have a great chance of mechanism failure. A few of the signs are bad performance, freezes, BSOD crashes and reports of Windows. For this reason I urge you to only run the health test of HDTune for now, until it's confirmed and the go-ahead is given that the drive is capable of handling the rest do not run any other test or benchmark.

Diagnostic Test

 RAM TEST

Run MemTest86+ to analyse your RAM. MemTest86+ - Test RAM - Windows 7 Forums

   Note

MemTest86+ needs to be run for at least 8 complete passes for conclusive results. Set it running before you go to bed and leave it overnight. We're looking for zero errors here. Even a single error will indicate RAM failure.

Make a photo of the result and post it.

Addition:
If errors show up you can stop the test, remove all sticks but 1 and test this single stick in each slot for 8 passes or until errors show, switch sticks and repeat.
If errors show up and you see them a lot later, no problem, the errors don't affect the test.

Diagnostics Test

 HDD TEST

   Note

Please run HDTune first, in the order posted!

Run the tests on all hard drives/partitions!

Run HDTune to

• check the health,
• scan for errors, no quick scan but full scan
• run a benchmark.

It may take some time, but please take the time you need to perform it properly.
When above is done please make screenshots of the following

• the health,
• the error scan,
• the benchmark incl. following
  
  • transfer rate,
  • access time,
  • burst rate,
  • cpu usage.

Run SeaTools DOS to check the integrity of your HDD. SeaTools for DOS and Windows - How to Use - Windows 7 Help Forums
Run the long test.

   Note

Do not run SeaTools on an SSD as the results will be invalid.

Make a photo of the result and post it.

Run chkdsk
Disk Check - Windows 7 Help Forums
Use option TWO with parameter /r
Upload the chkdsk log Check Disk (chkdsk) - Read Event Viewer Log