Partmgr.sys controls the Page File, which, if the PF's become corrupted, will prevent Windows from working (even loading in some cases).
If you're fortunate enough to have access to "Safe Mode" ignore the instructions for "BartPE" and go straight to Control Panel.*
What one needs is an HDD independent, bootable from CD operating system.
As no Windows OS has the facility to create one, go here: click here and make one yourself. Do follow the instructions and install XPE, as this holds the key to accessing "Control Panel/System".
OK, Once you've booted up into "BartPE" (with XPE), go to (Explorer) *Control Panel, then System, then the Advanced tab, then "Performance" button (Settings), then the "Advanced" tab and hit the Change (Virtual Memory) button.
Once in the Virtual Memory tab, you will probably see that the page File size is Zero Mb. This is your problem.
So: Highlight HDD, put a dot in the bit that says: "System managed size," press the button that says "Set" and then OK.
This may be followed by a warning box that says there's already a file called "Pagefile.sys" in this location, would you like to replace/overwrite it? Yes/OK is the correct answer.
Exit all tabs and reboot.