Not long ago, I received help solving a problem relating to trying to install a graphics card. We finally got it figured out, but two or three times since then I've had the following problem: I try to wake my computer up from sleep, and instead of coming back on normally, I get nothing on the screen and a fan can be heard blowing very loudly, much more loudly than during normal operation (this also occurred during the previous graphics card issue, but was more consistent). I shut it off by holding the power button, try to power it up again, and the fan blows loudly and there's nothing on the screen again. The most recent occurrence was just a few minutes ago, and after going through this a couple of times and then waiting a couple of minutes, it started up correctly. I seem to remember something similar happening a year or more ago, but never happened again until now.
The computer is a prebuilt HP h8-1380t. I'd appreciate any help I can get.