ksysguard, System Monitor, ppp0, graph faulty

[giovanni_re]

KUbuntu 10.4, quad core proc, 4GB RAM, plenty unused swap, plenty CPU availability.
ksysguard with 1 second update times.

Recently (past week or so?) the sys monitor program, which i've used for several years, has been screwing up the graph of rate of PPP0 data _&_ packets (two graphs).

A) Instead of a smoothish graph peaking at about 16KB/s, with a fairly even level graph, 
B) it goes up & down from zero to ~39, 52, 80 KiB/s, 50, 30, 60 80 packets/sec.

I have other programs that monitor the rate - KNetStats & NetHogs & IPTraf - & their displays havent changed.  So, it seems that the problem is with ksysguard.

Anyone know any info / suggestions about this? Anyone heard of this, or similar misbehavior?

Thanks. :)