I've read thru dozens of possible solutions on the web. Can't believe there are dozens of possible causes to this vexing problem of a blue screen after doing a Vista log-in. I was about to render my laptop a very expensive Frisbee out a 10-story window. Thanks to many well meaning souls out there who came up with their own solutions, I tried one after much trial and error and solved my problem (I realize not everyone is going to have the same cause/solution).
What worked for me was someone's suggestion to boot to safe mode with command prompt, type the MSCONFIG command, disable all startup programs and disable all services. By process of elimination, I found the culprits to be Windows Event Collection and Windows Event Logging. Still using MSCONFIG, I disabled them, re-booted, renamed \windows\system32\winevt\logs\system.evtx to
\windows\system32\winevt\logs\ystem.evtxOLD, re-booted, enabled the two previously disabled Windows Event services in MSCONFIG, re-booted. After logging in, checked Event Log in Control Panel/Admin to make sure it was working. MSCONFIG is a life saver.
Again, my thanks to those who have toiled with this problem and offered their solutions.