Sony Vaio...

I have a Sony Vaio VGN-FS790. Windows XP SP3 I've always set it to where I short press the power button to put it in standby mode and short press it again to wake it up. Just recently it starting acting up. When I short press the power button it puts it in standby mode but the "power on" light is still active. And also when I try to take it out of standby mode by my usual short press it fails to do so. So I end up having to long press the power button to get it to completely shut down. (Which is not what i want to do every time.) Basically, I just want my Standby function back. If you guys could give me some suggestions I would gladly appreciate it.

A few different things can cause issues with standby. Unfortunately, Windows XP was never very good at standby and your experience is common.

But, usually one of a couple of things cause the problem. Newly installed, or malfunctioning software; Malfunctioning drivers; or a bug in the BIOS firmware. Other times, it just doesn't work - period. And the solution is to turn it off.

Have a read through this article from Microsoft: http://support.microsoft.com/kb/907477

Your best bet is to decide what software or hardware you recently installed as that is probably your problem. You may also try to download and install the BIOS firmware update from the manufacturer's website. Sometimes taking a look through your event log immediately surrounding the standby and wake events might reveal what the probelm is.