I have seen the same problem, and so far the same resolution on a refurbished Dell Inspiron 531 (2.3 GHz Athlon)
[EMAIL PROTECTED]:~$ uname -rv 2.6.22-14-server #1 SMP Tue Feb 12 08:27:05 UTC 2008 This is with acpi disabled as listed above. If acpi is enabled, cpuinfo only shows one processor [EMAIL PROTECTED]:~$ cat /proc/cpuinfo processor : 0 vendor_id : AuthenticAMD cpu family : 15 model : 107 model name : AMD Athlon(tm) 64 X2 Dual Core Processor 4400+ stepping : 1 cpu MHz : 2310.606 cache size : 512 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 2 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8legacy 3dnowprefetch ts fid vid ttp tm stc 100mhzsteps bogomips : 4624.59 clflush size : 64 processor : 1 vendor_id : AuthenticAMD cpu family : 15 model : 107 model name : AMD Athlon(tm) 64 X2 Dual Core Processor 4400+ stepping : 1 cpu MHz : 2310.606 cache size : 512 KB physical id : 0 siblings : 2 core id : 1 cpu cores : 2 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8legacy 3dnowprefetch ts fid vid ttp tm stc 100mhzsteps bogomips : 4621.03 clflush size : 64 -- Second core in AMD Athlon(tm) 64 X2 Dual Core Processor 4800+ not recognized nor will pc power off when acpi enabled https://bugs.launchpad.net/bugs/144533 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs