I have had both the D875PBZ and DP965LT boards. No trouble with S3 and Resume. I have had three DP43TF boards and all of them have lockups when resuming from S3. I use PS/2 for mouse and KB. I have the latest BIOS installed. XPPro all patched and up to date. NV9800GTX GPU latest driver.
S1 works perfectly.
Can someone give me a clue as to what the problem is.