I cant extract my EPW.zip it always says " The Archive is either in unknown format or damaged" badLy need some heLp..
Try to turn off antivirus while extracting plus use 7zip to unpack it.
If it doesn't work, then it seems your client got damaged while downloading and then I would suggest you to re download but this time using torrents - you can pause/resume downloading any time you want. Also during that, you can turn off anti virus as well - just in case.