I just installed Slackware 14 to my main system and at beginning of boot it stops and I get the message "undefined video mode number 316 press enter for list of available modes or wait 30 seconds".
After pressing enter and choosing a video mode (324) everything works normally until next reboot when I have to do it all again.
my system is a HP Pavilion p7-1037cb, Athlon2 645 quad core processor, Ati Radeon HD4200integrated, 8GB DDR3.
I have no idea what I need to modify to get it to use the 324 video mode rather than try to use the undefined 316 and any help would be wonderful.

In your lilo.conf add "vga = 324" instead of whatever it says now (vga = normal, etc).

If you use grub add "vga=324" to the end of the line that specifies the kernel.

lilo requires a decimal number (the kernel is using hex numbers in that list)

When you look at Slackware's default lilo.conf you will see a bunch of options commented out that you can use (they are already in decimal)

EDIT

Don't forget to run lilo after you change it