Dear Sirs. I use FreeBSD 5.3-STABLE, most recently updated and built-world today. I realised strange behaviour with the used ASUS CUR-DLS mainboard and FreeBSD 5.3-{RELEASE|STABLE}. SMP is impossible on this mainboard with FreeBSD 5.3. With or without ACPI enabled, the machine crashes after a while (this 'while' is in the range of several minutes up to a whole day). The crash with SMP enabled is as follows. The system gets stuck, I can move windows around, but I can't open new xterms or other applications, network is dead then. The, after a while, the system reboots or gets completely stuck without any error. In some rare cases I 'suspect' the machine's crashing and I'm able to switch to console and see some debugger messages, most time they are heavily truncated. Also common on this machine (either in UP or SMP) is a not working single user mode. Doing a make installworld dies with a stuck console, typing Ctrl-T reports in nearly 100% of all cases process_foo [biowrd] or something similar. Starting single user kernel from loader without SMP and without APIC seems to solve problem, but compiling a kernel without apic remains the machine in a weird unuseable state (hanging X11/mouse etc.). Another strange thing is enabling/disabling USB, SIO ports and in what slot to put a 64 Bit PCI 1GBit NIC (intel 1000/Pro). Disabling both sio-ports makes the kernel stuck after initialising the SCSI controller all the way. Swapping NIC from on to the other 64 Bit slot decides wheter I can use a further 32 Bit add-on card (audio board) or not! This seems to be a IRQ routing problem which is well known to me since I utilize a TYAN Thunder 2500 mainboard with FreeBSD (without ACPI). I did several PR-reports in the past and i was told my problems were hardware related but I think this is not the truth since in UP the machine is stable (except single user mode) and I get weird behaviour with APIC off (stable, useable single user mode, non working multiuser mode). I also get a stable single user mode when inserting another VGA (PCI type) video board: single user mode is stable, not getting stuck, but machine dies immedieately and reboots when booting the FreeBSD kernel in every variation (with/without apic/acpi/up/smp). Before reporting again masses of faulty bug reports or nonsense not suitable for gurus or developers, I would ask you whether someone out here utilizing the ASUS CUR-DLS mainboard and using FreeBSD 5.3-XXX has the same problems or not. Many thanks in advance. Oliver