Not staying in standby

My Toshiba laptop isn't staying in standby. If I go to standby at the welcome screen, it stays. But if I go into my "profile" and go to standby from there, it only goes to standby for about 1-4 seconds, then comes back out and opens up again. I think this started when I installed AVG free, but why? My main rig stays in standby and I have AVG on it. I'm no positive it's from the AVG, but I know something changed and now it won't stay in standby, even without the ethernet cable attached. Even with AVG closed it won't stay in standby. Of course I need standby, so what's going on?

Bump

You probably have a program running in the background that triggers it from standby mode. I would check your task manager and try stopping programs one at a time till you find the culprit. I know it's tedious but I'm sure you'll find the program quickly.

In addition, check the settings for each of the devices in Device Manager. Expand each hardware device entry (Keyboards, Mice and other pointing devices, etc.), right click each device and select "Properties"... which will bring up the "Properties" applet. Look for a tab called "Power Management", and uncheck any settings to allow the device to bring the computer out of stanby.

Also check the BIOS settings for any "Wake On" settings and disable those.