Blue Screen - winlogon.exe - Application Error

Hi, I am hoping someone can help me solve my blue screen problem.  I spent the entire weekend working on getting rid of it, but it hasn't gone away.  I am really frustrated and tired.  Please help, if you can.

 

Here are the error messages:

 

MESSAGE 1 (appears during windows log on):

 

winlogon.exe - Application Error

 

The instruction at "0x77d4d1a7" referenced memory at "0x00000008".  The memory could not be "read".

 

Click on OK to terminate the program

Click on CANCEL to debug the program

 

Clicking on OK or CANCEL causes WINDOWS to terminate.  If I don't click on  either OK or CANCEL I can manuever through Windows and even use Internet Explorer.

 

 

MESSAGE 2 (blue screen if OK or CANCEL is selected):

 

STOP:  c000021a {fatal system error}

 

The windows logon process system process terminated unexpectedly with a status of 0xc0000005 (0x0000000  0x0000000)  The system has been shut down.

 

I was able to back up my hard drive.  I removed some photos, videos and temp files, checked for windows upgrades, ran disk clean up, and defrag.  I am using McAfee and I also have Zone Alarm.  I ran Ad-Aware and deleted some cookies.  Updated Adobe Acrobat Reader.  I ran chkdsk /r in Safe Mode and tried to run sfc /scannow.  I've also noticed that the Event Viewer is identifying errors.  I tried running memtest86 but couldn't because I can't unzip it.

 

I have never had a problem with the blue screen until last week after I had added several photos and viewed a homemade DVD containing videos and photos (with some errors)....my hard drive was getting full and hadn't been defragged in awhile.

 

I will appreciate any suggestions.....Thanks!