Ok, by the Gagp30kx.sys I think you mean that safe mode stops loading that driver and restarts.
Since its name is agp, that's related to the video card driver.
You can rename the driver in safe mode (if it lets you), if not (as I think!) use the Recovery console, (by booting from cd and pressing r while cd loads, then go to
the system directory and rename the file) and your computer is likelly to start...
But the problem is it won't recognize you video card anymore, so you have to redownload and install the video drivers and maybe even the chipset ones...
See here for some details:
http://www.geekstogo.com/forum/topic/286491-missing-gfx-card/