Every few hours, all of the WCG science tasks running in BOINC die simultaneously with the message in the title, and then restart automatically. This has been happening every few hours for some days. Not a single task (WU) has returned an error or invalid result.
The system almost freezes during the turmoil.
It has been happening only since starting to run DDDT2 tasks (4 of), but also happened at least once running 4 x "c4cw" Beta WUs. The machine has run a mix of FAAH/HFCC for months, without one hiccup.
DDDT2 tasks reserve 500MB of pagefile each (VM size in task mangler), and I thought that might be the problem, but it's got 4GB pagefile allowance, and you get a different effect if you bump into that limit when suspending a task. (Been there, done that. Fun. The error logs have the right diagnostic messages too.)
Physical RAM should not be an issue

I thought it might be my overclock settings, as I suspect that the DDDT2 program (CHARMM) is more critical than the other WCG science programs. I've upped Vcore and Vmch. Decreasing FSB speed 1 MHz at a time does not seem to alter the frequency at which this is happening, though I haven't backed right off. It's only happening on 1 machine - the others are OK.
Prime 95 (1 x small, 1 x InPlace, 1 x Custom 513MB, 1 x Custom 97MB) is stable last time I tried it.

Has anyone else seen this?

[Am posting here, not WCG, because of the overclocking]
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Q9650, 448x9 = 4.03GHz, Vcore = 1.24,
Asus P5Q dlx, Vmch = 1.34, Vtt = 1.24
2 x 1GB Corsair PC2-8500C5, 5:6 (1074MHz), 5-5-5-13 PL=8, 2.06V
500GB WD green, no video.
XP-64 SP2, all updates applied. BOINC 6.2.19, 32-bit.