but as a caveat, I can tell you that if the problem persists, it may still be with the installed software. In that case, back up all your data, wipe the drive with something like DBAN, and do a clean install.
One thing you can do, which I should have mentioned previously, is to take a look at the event logs to find if there is a reference to the error and any relevant conditions immediately preceding it, or anything reported since the game was started.
DxDiag will only reveal the capabilities of the hardware, it will not necessarily reveal any problems, particularly if the tests do not create the create the environment in which the error occurs, or are run at a time when the error is not occurring.
The error you actually see may have nothing to do with the cause, but may be a result - there is an attempt to clear memory for use when the game is terminated, but nothing is found at at least one address referenced.
Do you use a graphics card or onboard video? This is relevant since the error is in system RAM. Graphics cards have their own RAM.
And since were here, what is you system make and model number, what OS are you running?
What security software are you using?
Did this problem occur after you had installed anything else? Were there recent OS updates, other software updates?
I've cleansed the PC of malware.
So, you are saying there was malware? If so, boot in Safe Mode, turn off System Restore, and run malwarebytes and whatever other tools you use until nothing shows up. But, removing malware doesn't fix the damage it causes, so a repair or clean install may fix you up.
Sorry to be so wordy, but I'm trying to cover as many bases as I can. The problem and error message are so vague that that they don't lend to easy diagnosis, especially over a forum thread. ;)
Oh, and you might just want to try the MS memory diagnostic as well, just in case.