I recall having a "memory can not be written" issue with a game once, but I don't think it was Mass Effect. This is what I remember doing at the time...
I've also done a number of searches with the information that you've provided to see if can find another solution, but I haven't found anything that isn't already listed in the threads linked to above.
The exact text of the error message may help pinpoint what the issues is.
Folders and files were checked as read only so changed that and then tried again and got this error
.png){kind=link}