This error appears when starting up Guild Wars. Experience has shown it to take 10-30 minutes to fully recover depending on the speed of your computer and internet.
Repairing Data Archive will make you download some game files again. The number of files may vary.
If the problem persists, exit the game, go into your Guild Wars installation folder, rename
GW_backup.dat and run the client with the
-image command line argument. After the download is complete and the game is working again, you can delete the backup dat file.
Warning: if you get this error frequently, it may indicate problems with your hardware, such as bad RAM or HDD sectors. It may be worthwhile to run a memory check: