Tyan S2932-E suspend to ram fails to resume

[Simon-]

When I suspend my system (from Linux 2.6.27-rc1), it turns off and then fails to resume.

When I press the power button, the port 80 display shows:
FF D0 23 01 D0 ... DE
(and again each time I press reset)

If I force it to turn off, then on again:
FF D0 23 01 D0 ... FF D0 23 01 D0 ... (D2?) D3 00 01 D5 D6 <normal boot>

The BIOS image is in ftp://ftp.tyan.com/bios/S2932-E_v202.zip, could someone tell me what the DE code is indicating? It's not mentioned in the motherboard manual...

Motherboard: Tyan S2932WG2NR-E
CPUs: 2x Opteron 2354
RAM: 1x Crucial CT2KIT51272AB667 per CPU

I've tried disabling ECC, on-board LAN/SAS/USB (but not SATA), and removing all PCI cards.