HELP. BlueScreen? Don't know what's going on.

Question

I own a Lenovo T500.  Have owned it since December, 2009.  The computer will sometimes react in one of the following ways:
1 - It emits a loud buzzing sound and freezes.  This continues until the computer shuts off and restarts.  The buzzing sound is, I imagine, the result of audio freezing [music or video].
2 - The screen simply goes black and stays that way until the computer shuts off and restarts.  No sound.  Just a black screen.
This happens on and off, sometimes going days without an incident, and other times happening 8 times in 6 minutes [like today].  I am furious, and do not recall when it started happening, exactly.  Google searches have led me to believe that this is related to my video drivers not functioning / needing to be updated / etc.  Can anyone tell me what is wrong here?
The last two messages the computer displayed on startup were:
Problem signature:
  Problem Event Name:    BlueScreen
  OS Version:    6.1.7600.2.0.0.256.48
  Locale ID:    1033
Additional information about the problem:
  BCCode:    a
  BCP1:    0000000000000000
  BCP2:    0000000000000002
  BCP3:    0000000000000000
  BCP4:    FFFFF800031FE477
  OS Version:    6_1_7600
  Service Pack:    0_0
  Product:    256_1
Files that help describe the problem:
  C:\Windows\Minidump\050811-43539-01.dmp
  C:\Users\FAAAKE\AppData\Local\Temp\WER-58079-0.sysdata.xml
----------------------------------- and -----------------------------------------------
Problem signature:
  Problem Event Name:                        BlueScreen
  OS Version:                                          6.1.7600.2.0.0.256.48
  Locale ID:                                             1033
Additional information about the problem:
  BCCode:                                               a
  BCP1:                                                    0000000000000000
  BCP2:                                                    0000000000000002
  BCP3:                                                    0000000000000000
  BCP4:                                                    FFFFF80002C14477
  OS Version:                                          6_1_7600
  Service Pack:                                       0_0
  Product:                                               256_1
Files that help describe the problem:
  C:\Windows\Minidump\050811-44148-01.dmp
  C:\Users\FAAAKE\AppData\Local\Temp\WER-59717-0.sysdata.xml
SOMEONE HELP.  PLEASE.

Answer 1

which T500 do you have? i.e. does it have switchable graphics card?
if it does, try switching to intel gpu, does the same problem occur?
Regards,
Jin Li
May this year, be the year of 'DO'!
I am a volunteer, and not a paid staff of Lenovo or Microsoft