strange dmesg entries

[jack]

Every once in a while, my Kubuntu 7.04 box will just lock up for about a
minute.  Granted I'm probably just running alot of applications, but it
seems to always be centered around Evolution.  Anyway, If I jump to an
alt terminal login, running dmesg shows me a whole run of these preceded
by what appears to be a process id and some other number that I'm not
sure of - 
[2030.152001448] VMBlock warning: DentryOpRevalidate: Invalid args from
kernel

Any ideas what might be causing this?

Thanks for any input.

(it took over 10 minutes just to type this message...)