See that area in the lower left-hand corner that says "Read-only"? That means that Windows won't let ANYTHING overwrite that file. As such, you can't save your alterations unless you remove that setting. Just like a Floppy disk won't write when you have the little switch moved. That saved the company my dad worked at once... They had lent out one of their PCs to another company. When they asked for it back later, the barrowers didn't want to return it. When they did, the PC was completely filled with all kinds of viruses. They were so intrusive, that even error dialouges (like, when the PC can't write to a floppy) didn't show. It just kept trying to write to the disk, but couldn't because they had it write protected. Whoever it was that barrowed that PC is a nice guy, I guess... [/sarcasm].
Anyway, hopefully that helps. Mouser X over and out.