on boot, no sound device is detected and there is nothing in event viewer that states error
everytime my PC boots up, the sound card is disabled, and there is no yellow exclaimation point
however, I can go to device manager and enable fine, but have to do this manually after each reboot

PCI\VEN_1102&DEV_0006&SUBSYS_10031102&REV_00\4&1C660DD6&0&10F0: Creative SB Live! Series (WDM)

how can I find what is preventing sound on boot

Download a new driver from the manufacturers site then use this guide below to delete the existing drivers and any old ones. Then install the new driver.

http://www.howtogeek.com/howto/windows-vista/remove-old-drivers-after-upgrading-to-new-hardware/