Gw.dat Problem!

I had to reinstall Guild Wars, and rather than re-download it, I opted to copy my old Gw.dat file into my Guild Wars folder. The problem is that when I run Guild Wars now, I get a red error message saying:

Unable to open archive file, please make sure gw.dat is accessible and writable, and no one else is using it.

I have the file completely copied into my GW folder, and it is not being used by anything else.

Any insight?

Yea, just redownload it instead of copy-pastying it o.o

You could always check whether the file is Read Only?
Right click on the file, click properties then uncheck Read Only and click Apply

Did you back it up to a DVD or something? I don't know for sure how it works with Data DVD's, but long ago I had backed up some files to a CD and when I put them back into a game I got problems like that, because once it's on a CD, it becomes read only, and when you copy it back to the drive, it ends up being read only on your drive after.

my steps in this situation would be:
1) check if the file is marked read only.
2) if not, reboot
3) if it still doesn't work, delete it and redownload everything

The copy-paste method works fine, I've used it in the past. You just need to make sure that the file is not marked read-only.