[Updated Mar 18]
The 2.6.20.3 also gives problem in network connectivity. At this stage I am not sure if it is the kernel or the RT61 network driver, though my gut feeling is the latter. For now I am reverting back to the 2.6.18.3 version, until I have time to fire a debugger and play with the issue.
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I had been experiencing network connectivity issue on 2.6.20.1 kernel. It is supposedly a stable release, but in fact it isn't. I just downloaded 2.6.20.3 kernel and hopefully the issue(s) are addressed (After one hour of running, it seems I can still edit this blog entry fine...)
If you are running 2.6.20.1 kernel, an upgrade is nearly mandatory.
As a side note, Minix is out with version 3!! It has its own site here. Minix is using a microkernel architecture and was first written for educational purpose by Andrew Tanenbaum, a renown professor.
If you are more OS-inclined, the wikipedia entry above has a lot of interesting stuff, which can safely kill hours of your time. Enjoy!