2.4.20: hang on "ls -lR / >file"

[Jack]

I do "# ls -lR / >/root/ls-lR"; and at some point (non-deterministic) my 
system locks up hard (e.g., sometimes software watchdog even detects lockup)
confirmed several times
once i did "# for i in /*; do ls -lR $i>>/root/ls-lR; done"; it 
succeded, when i did "#less /root/ls-lR" afterwards, it hung up again.
kernel 2.4.20 ; gcc-2.3.2; glibc-2.3.2; originally was slackware-8.0; 
athlon cpu on asus a7m266 mb
ibm 60gxp thru onboard via southbridge and maxtor 6y0l0 thru promise 
ultra66 add-on card (pdc-smth)