I have three possible solutions for you that I will suggest in what I hope is the best order to try them in.
1. TRY EDITING IN ADMIN MODE:
Open notepad in Administrator mode, by searching for it, right clicking and select 'Run as Administrator'. Now from the file menu choose open and open the file that you were unable to edit. Attempt to edit it. I am aware of a 'feature' in Vista where some files marked system couldn't be edited unless you were in administrator mode. This is the easiest way to rule this out for you.
2. SOLVE A DRIVER
READ ONLY PROBLEM:
One of my customers had a similar issue with a new Windows 7 Install. The problem had nothing to do with permissions. In fact all the permissions I checked were correct and like on your example, the read only attribute was greyed out.The correct solution for me was to update the SATA drivers
with the latest ones from the manufacturers website. In my case this was for the Gigabyte EP45 motherboard. Please check that your hard drive drivers (be they sata, raid, IDE or whatever) are the latest for Windows 7 that are available on the manufacturers website (not through Microsoft update or driver software).
NOTE: If you check through the Microsoft Update Driver Software service, you will only get the latest drivers that Microsoft is aware of. Sometimes this just means the Microsoft default drivers which might appear to work; but may not offer all the features or reliability of the manufacturer drivers.
By the way, if you do find and install new drivers and the problem still exists, check the permissions again as discussed previously in this thread (using the TAKEOWN script should suffice); the new drivers may offer changes here.
3. CLEAR READ ONLY WITH THE MS DISKPART CMD TOOL:
If you are still unsuccessful, you can use the diskpart command line utility to clear readonly attributes on your hard disks. I have attached a bath file that I wrote that will do this for you, on any system that has up to 10 disks installed. If you have more then 10, then I can talk you through it manually or adjust the batch.
To run the batch file:
a) save it anywhere
b) open CMD in admin mode
c) cd to the directory that you placed the batch file in.
d) type the name of the file to run it.
EDIT: Just to rule it out (and you most likely already checked :-) )
- Do a full checkdisk on the drive
- Run the attrib command on the file (from CMD in Admin).
- Make sure that Flightsim has no files open when you try to edit. Just check the task manager to rule this out.
attrib -r -s -h