Possibly this is due to interrupt activity.  Plugging in an ethernet cable in the same time window also hangs system.

This makes it seem like the issue might relate to not masking interrupts, or at least those originating in the outside world.

Note that neither of these glitches were seen on the same hardware with 2.6.36/cooking (updated late December)

I'd still like to see where you found an iso that was made on the 19th of March. The last Cooking iso update was the 1st of March under the undigested (read unreleased) iso, with the upgrade to kernel 2.6.37 being made in January. The prior undigested was yes, for December (26th if I rememeber correctly). Mind you, the old cooking iso from November is still the one provided on the main website.

Can you please clarify which version of cooking you're using and the steps you took to get there, then maybe we'll be able to help you better. Did you upgrade via packages? Did you download the latest cooking from http://mirror.slitaz.org/iso/undigest/ ? Did you install or compile any packages that might be contributing to this? Please provide more information that guess work and a cooking that doesn't exist.