asus p5ld2 stand-by and hybernate problems

Hi everyone, just upgd from p42800 + asus p4p800 to a new asus p5ld2 + dual core E6400 + winxp sp2 and same hardware as before except for an ati X850 pciexpress.
Everything works fine apart standby and hybernate as follows:
- Standby works just with APM mode S3: all other modes doesn't restart the video stuff and the monitor still black.

- Hybernate no works at all: winxp start hyb procedure, finish and stops the pc. At the reactivation, winxp restart the machine but after the progressbar everything locks needing hardware reset to restart.
Also, during the restart after the hybernate, the mboard boots up again instead to restart immediately.
Tried to stick with APM but no big differences.
What's wrong ?
Tia for every help