hello. whenever i run guildwars then check the task manager, it's set on low priority. i switch it to high, close the task manager, then open it back up and it's still on low priority. alot of other ppl have this issue and i asked around some guildwars forums without getting a fix.
My guess it it auto-switches to low priority when you aren't full-screen or playing the game. That's why whenever you check it on task manager it shows it as low priority even after you have set it to high but after you set it to high priority when you actually click back to the game it is running as high priority. Even if that's not the case it shouldn't be an issue unless you are getting slow performance. If not I wouldn't worry about it.