Alright, I see that Adamar has seen the ticket and classified it as a duplicate ticket reporting an existing known issue. This means that the developers know the issue, acknowledges it is affecting some people, and there's probably no workaround for it until the next Curse Client beta update.
As for what you can do, I suggest you try moving your wow's install location. See this thread to see the default install locations of wow (its different, depending on windows version, and even wow patches):
I suggest you move your wow folder out of C:\Users\Public or C:\Program Files\ or C:\Program Files(x86)\ and run it from some folder such as C:\Games or D:\. You just need to run wow.exe from the new location (just move the whole wow folder to the target location you want it to be) and wow will update the windows registry as to where the install location is.
Vista and windows 7 has some UAC stuff that prevents wow from writing addons to a non-public folder otherwise, or to c:\program files\, and this affects all applications - including the curse client.