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...
- Make sure all drivers are up-to-date.
- Make sure game folders are not checked "Read Only.
- Run the game as an Administrator.
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.
