Windows has never really handled standby very well and there has always been issues.
Here are just a couple of discussions about standby in these forums. There are many other posts you can find usng the Search option;
It may be be easier if you ditched standby and hibernate for simple screen saver and turn off the monitor, or complete power down, whenever the computer is to be unused for a while.
I purchased a VAIO desktop VGC-RB42G in August and it initially worked fine. A few weeks ago it would reboot after waking from standby. Then it would need to reboot multiple times. It was apparent it would get further with each reboot. I got an error that windows did not start properly with the option of starting in safe mode, going to a previous configuration, or normally. SONY Support recommended going back to a configuration that pre-dated the start of these symptoms but there was no change. Then this week Windows (XP Media) would not start at all. SONY support recommended reformatting. I dod so and put some of my basic software back ( Verizon internet, Office, Sonic Stage 4, Avast) but still no change. SONY Support said if the reformat didn't work there is a hardware issue. If I turn off standby there is no issue. The machine will reboot fine. Short stand bys are not a problem either. This problem requires a stand by of a few hours at least. At one point there was an errorand the report went to Microsoft. I got back a message to visit the Intel site where there the recommendation weas to update the display driver. I did that before the reformat and no change. Before I go to SONY service I was hoping to collect your opinions. Thanks.