Oscar,
You 110% certain there that you did indeed, set it to NO LONGER wipe the pagefile.sys contents?
(That takes time to do, & judging from your 'symptoms' there, it's looking as if it is STILL doing it... )
Maybe, just maybe, you have not done it properly to undo it! It's possible & does sound that way, as if it is STILL attempting it...
(I know, I am asking you to double-check but humor/indulge me, do so again, but this time... manually in the registry itself in the path I show you below to follow!)
* In fact, look here in regedit.exe's left-hand side pane of tree hive items ->
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
And, in the right-hand side pane, be sure the ClearPageFilesAtShutDown is set to 0 (ZERO) false value!
(Make sure that is set to a ZERO/FALSE value manually to be absolutely 110% sure, by looking at its settings in the system registry hives itself!)
APK