Goes to sleep while active

Hello folks.
I've got a very annoying thing happening with this new machine (Home Premium x64). It seems to go to sleep based entirely on how long it's been since I touched the mouse or keyboard. If there's a program running, like a virus scan or a download in progress, it goes to sleep right in the middle of it. That's incredibly stupid!
How do I make it stay awake when it's in the middle of doing something, even if it's not receiving input from me?

Thanks

No, it's not the blank screen saver, it's going to sleep. If it was the screen saver, it would finish its task, and it doesn't.

And I see at the bottom of this screen a link to someone else having the same problem.

It's abysmally stupid if Win7 can't even tell when it's active and when it's not!

No, I have it set to go to sleep after 15 minutes. I know about power settings. But when I set it to 15 minutes, I never guessed Win7 would be this stupid.

This is "the best Windows"? Goes to sleep in the middle of a job and the only way to fix it is to turn off the power-saving settings?

For crying out loud, did they have 7th-graders writing the Win7 code? When the timer runs out, check the cpu to see if it's doing something... check your internet connection to see if data's coming in... If the answer's yes, DON'T GO TO SLEEP!

Windows XP works the same way unless the software running is specifically designed to keep the machine awake.