What does this Apple Hardware error Code mean 4 SNS/1/40000001:'VDOR' My iMac OS 10.4.11drops out when starting up.

Apple does not publish what the codes mean, however it clearly indicates you have a hardware fault. I STRONGLY advise taking the computer to an Apple Authorized Service Provider in your area who can professionaly diagnose it. This will likely save you money rather than guessing what the problem is. If you don't know of any in your are you can begin finding one by clicking AASP Locator

According to the list I've been able to amass, SNS means System Sensor - as mentioned, a hardware fault. So, Apple store or authorized service provider is the next step - there is nothing you can do. Hopefully you have a current backup.

Just FYI, downloading a video takes up space on your hard drive and you should make sure that you have at least 10 - 15 GB of empty space available at any time.

That code references the DC voltage sensor. You need to take your iMac in for service as mentioned above.