Lack of memory/ wallpaper is gone

Scaleo

Honorable
Mar 7, 2012
239
0
10,680
Help needed!

Today I left the pc on for 3 hours without using it, when I came back I noticed it was perfroming really unstable, the cursor was laging, and a message popped up saying that there was a lack of memory suggesting I should restart the pc, wich makes no sense since I only have one non-Windows program running, Steam.
I open op taskmanager to see if I could see what taked up 8GB of RAM, but the program that took occupied most RAM was around 80MB big.
So I decided to turn the pc off manually, wich resulted in it not responding the first time, so I issued the shut off again, screen went black, monitor went in to standby mode but the pc was still operating so I had to turn it off via the powerswitch, turned the pc back on in 1 hour and noticed that the background was completly gone (black), I changed it without problems back to a background and seen no problems yet, should I be worried about this? What could have caused it? The pc is still under warranty so I have to know if it is critical and I need to send it back or if it's a minor glitch.

Thanks in advance