So, I thought my vintage IBM T21 was toast. I stripped the only parts of resalable value, HDD, PCMCIA card & RAM.
I reassembled to trouble shoot, resulting in a new fault. My animated Plymouth splash was sluggish & opening either Firefox or Chrome would peg the processor & thrash the hard drive.
Strange I thought.
Turns out only one memory module was being detected (the HDD thrasing was swap being caned.) After reseating both sticks everything was back to normal. 256MB would appear to not be sufficient these days, even the default mode of Parted Magic, itself an LXDE environment, requires more.
The solution seems simple in retrospect.