I wanted to wait before I added my two cents, you never know what will work or what can be the cause. I’ve worked on computers for years since DOS was the name of the game. Lets go back to system basics and the details you have stated this far.
The big point I see is that you were able to render it fully at home but it took 19 hours.
I have had similar problems using different machines over the course of the years. The number one culprit was an over temp or an over temp limit value set in the bios for the CPU. To protect the CPU it will crash the computer but prior to reaching that point it will hang or produce errant results. Before anything further please boot up and get into your BIOS and check what your TEMP readings are for your CPU. The temps you are reading here are idle and should be well below the threshold. Also make sure you are not overclocking your CPU as this adds great instability and a huge amount of heat. These CPU’S will burn out in less than 30 seconds without proper cooling. Your CPU temp on a quad core should be well below the max limits. There is free CPU monitoring software out there that will give you live temps of everything from Mother board temps, graphic cards, to Hard drive temps. Few people ever think about the drives being a problem but they can be and often are. Do the basics and check those temps at both idle and processing. Render times can indeed take a very long time depending on the system config. For example..
1.Are you using separate drives for rendering? Is there sufficient space? Do not forget that Vegas uses a default for the Temp folder. So that you might have sufficient room on the destination drive but not enough on the primary. Also please allow at least 10 gigs of space on any drive you are using to render as windows does not accurately report the remaining disk space. For example it does not redeem anything in the trash until you empty the recycle bin.
2.Make sure you are allowing windows to handle your PF memory allocation size. Vegas only recognizes 2 gigs as I recall so if you don’t allow windows to handle this it will cause a crash every time under heavy processing.
3.Make a clean boot setup so that there is nothing running in the background. No virus, spyware, internet, etc. Anything that auto does anything is not good. NO SCREEN saver.
4.Power management settings should all be turned off. The last thing you want in a long render is for the screen to turn off or the hard drives to power down. Basically you do not want any CPU cycles to be interrupted by any other programs. My HP printer periodically checks the for ink levels and prompts me. Not good. Turn off windows update and anything else that automatically looks for the internet. It will still do it regardless of whether or not you disconnect the internet source so you have two choice, turn it off in the preferences for each software or create a clean boot with no services running. If you don’t know how to do that just ask. I’ve had renders and other operations ruined because of these annoyances. Again simple solutions first.
5.Try using a lower bit rate for rendering. I have one machine that bogs down if I use 32 floating point. Not all systems can fully use the feature…yes even a quad running Vista.
6.Turn off Preview render option of course if you using that feature and also minimize the window. Anything you do to free up resources will speed things up and cool things down.
ok I’m sorry if all this seemed rudimentary and for being long winded. I’m fairly well versed and still make basic errors like these. I hope this helps in some way. You need to diagnose the health of your system. Defrag your drives and perform a virus and spyware check. You never know. The systems I use to work with never see the internet….