@Zephyroth,
Thanx for your reply,I and splinter182 got the same issue---we do NOT even see the installer's GUI before reboot then how can we select kernel 9.x.x?The 10.5.1 Rev1 is perfect for my spec and I got the same problem when I installed PC_EFI_v80 manually after updating to 10.5.2 by eddie11c's package.Is there any known issue with EFI bootloader on Sempron? Anyone confirms?

@roisoft,
My Sempron 2800+:SSE2/SSE3,64bit.

Thanks!!

Regards!

Kael