Best bet if you don't want to lose you HC monk, don't mod the save file, just leave it alone. Hopefully you made a backup of your save file before messing with it, so you can just put it back with no problems.
As much as i have messed with my saves, i have never come across the issues you are having, sounds more like a bad hard drive rather then a bad save file, not sure though.
As much as i have messed with my saves, i have never come across the issues you are having, sounds more like a bad hard drive rather then a bad save file, not sure though.