FreeBSD 5.4-RC3 hangs on boot, 5.3 works

[Arjan Van Leeuwen]

I'm trying to install FreeBSD 5.4-RC3 on a Lex Neo system
(http://www.lex.com.tw, a small form factor PC with a 1GHz VIA C3
processor).

The system hangs when booting the kernel, at this point:

Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: VIA C3 Nehemiah+RNG+ACE (998.70-MHz 686-class CPU)
  Origin = "CentaurHauls"  Id = 0x698  Stepping = 8
  Features=0x381b93f<FPU,VME,DE,PSE,TSC,MSR,CX8,SEP,MTRR,PGE,CMOV,PAT,MMX,FXSR,S
SE>
real memory  = 125763584 (119 MB)
avail memory = 113414144 (108 MB)
npx0: [FAST]

A 5.3-RELEASE kernel boots fine however, and shows this in dmesg:

Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: VIA C3 Nehemiah+RNG+ACE (998.70-MHz 686-class CPU)
  Origin = "CentaurHauls"  Id = 0x698  Stepping = 8
  Features=0x381b93f<FPU,VME,DE,PSE,TSC,MSR,CX8,SEP,MTRR,PGE,CMOV,PAT,MMX,FXSR,S
SE>
real memory  = 125763584 (119 MB)
avail memory = 113414144 (108 MB)
npx0: [FAST]
npx0: <math processor> on motherboard
npx0: INT 16 interface
acpi0: <VIA601 AWRDACPI> on motherboard
acpi0: Power Button (fixed)
Timecounter "ACPI-safe" frequency 3579545 Hz quality 1000
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x4008-0x400b on acpi0
cpu0: <ACPI CPU (3 Cx states)> on acpi0
acpi_button0: <Power Button> on acpi0

Booting in safe mode, turning off ACPI in the BIOS of the machine and
changing 'PNP OS' to yes or no in the BIOS does not help.

Any ideas on what to try next?

Arjan