Hi ronhood4 and welcome.

Unfortunately it could be many things to include both hardware and software faults.

What exactly happens when you try to start up?  Are there any sounds/lights or is it completely dead?

I presume you are still using Vista? 

Firstly, I would start with software and try running the 'Startup Repair' by tapping F8 during bootup and choosing 'Repair my Computer' -> 'Startup Repair'.

I would then try to repair any corrupt system files by using the System File Checker by going to the command prompt and running "SFC /scannow.

Next, try running a Registry cleaner to remove debris accumulated over time.  Your Vaio may be searching for links to software that has been uninstalled or removed.

If those fail try checking your hard drive using Vista's error checking: -

http://windows.microsoft.com/en-us/windows-vista/check-your-hard-disk-for-errors

Next ..... start looking at hardware problems.