Dual Core CPU not seen after an upgrade to Karmic

[Brett Mahar]

> After an upgrade of my dual core AMD 4050e machine to Karmic, the
> second core is no longer seen (/proc/cpuinfo shows only one CPU).  I
> have never seen this issue  with Jaunty.

 I recently bought an eMachines desktop with an Athlon X2 5050e dual core
processor. I installed Ubuntu 64bit (9.10 Karmic) and it runs on dual cores with
no adjustments necessary.
Brett.