Problem after waking from S3 standby

I have small issue with a new PC using the 780g HD3200 chipset.
After resuming from standby, HD H264 video will not play, just a blank
screen, and I think it is due to the DXVA acceleration not working. If the
PC is rebooted, then all is fine again. As this is an HTPC, I use standby
frequently...
I think it unlikely that the H264 decoder could be the issue, but for what
it's worth I am using the MPC Home Cinema stand-alone decoders
MPCVideoDec.ax & Mpeg2DecFilter.ax, and the ATI drivers 8.452 from Gigabyte.
Are there any known issues with hardware acceleration not working after a
sleep state on ATI cards, or the 780g motherboards?