Just wondering if you ever found anything out for this? I am experiencing the same issue and it only happens with the Sony Drives, I have tried 2 different models one slim line and another full lsize and they both do the same thing. BIOS is updated etc.
Edit: I found that in BIOS revision 0081 and later the issue is resolved. What had me going the wrong direction is that Express BIOS does not work as advertised in Windows 7. Certainly not when you have a BIOS version that does not warm boot properly.
So for those experiencing this issue, simply use an alternate flashing method. I chose to DOS boot from a USB flash drive and run ezflash. Once you flash then it is key to reset your BIOS to optimal defaults (F9 inside the BIOS I think) then make any changes you want to the default settings. Of course verify the BIOS version on the main page to validate your flash update was successful.