PolideseusNZ I read over your dxdiag and don't see anything in need of addressing. But one of the most important details would be the error, if any, that happened at the time of this freeze. Because a dxdiag only lists the last ten Windows errors, it's likely that the one from the freeze has been crowded out by newer (innocuous, in your case) errors, so I can't see what happened.
If you're curious, you can find the old error yourself—the Reliability Monitor goes back 30 days. Click Windows key-R and enter "perfmon /rel" without quotes, and you'll see a chart of errors and updates with a column for each day. Today is on the right.
Look for an error that happened at exactly the time of that freeze. If you find one, double-click it to see more details, then copy that info and paste it into a reply here.
You can also wait until this happens again, if it does, and look for a new error at that time. If you don't see anything, check back in an hour or so—the Reliability Monitor doesn't always update right away.
In general though, when you have a one-time problem that disappears on its own, and you don't see any other signs of trouble, you can ignore it. Stuff happens, often for reasons that can't be explained without advanced or real-time debugging, and Windows is often capable of repairing simple problems before they take down your PC.
