Windows 7 - Close programs to prevent...

For some reason having this error message come up. Twice now in an hour

Close programs to prevent information loss: Close down this program: WoW

75% RAM usage which is normal when I'm playing a game so don't know why I'm having it.

Just after I also followed Guide * Windows 7 Ultimate Tweaks & Utilities *

I have also just noticed (pic) that it's using a lot of memory, surely more then usual.

Anything I can do?

Ty

Edit
Just had it again when RAM was at 79% Then I tried to load up chrome and got "This app was unable to start correctly (0xC000012d)

Do a memory test with Memtest86+ - Advanced Memory Diagnostic Tool for 6-10 passes. Better to start somewhere around night and leave it on as it'll take much time.

Did one 7 days ago and all fine. Will do tonight again with both sticks in.

Can't do 1 stick at a time because:

I simply don't have the time to mess around. My CPU fan (TRUE) would need removing, then buying some paste and using stock cooler again, then doing hours of tests. Last time for 7/8 passes it took 9 hours so.