. it is simply "incompatible" with your declaration: It is not anything particularly difficult/complex, but you have first to get familiar with the procedures. Additionally (and unfortunately) there are at the moment several reports of "generic" issues with MS servers (or with Windows Updates or both), so that a lot of people, also those that know how to do it, are having issues in downloading symbols, see the "main" thread: http://www.msfn.org/board/topic/170850-aero-glass-for-win81-125/?p=1089433 You may want to wait a few days, until the current situation is clear (or clearer), and use this time to learn a bit about Registry editing. Downloading manually the symbols can be tricky, but the queation is common enough: http://www.msfn.org/board/topic/170850-aero-glass-for-win81-125/page-108#entry1089424 and has been already explained in detail: http://www.msfn.org/board/topic/163570-aero-glass-for-win81-rtm-rc3/page-16#entry1058721 If you have issues in following the above, no offence intended, rest assured , but you are simply not ready (yet) for using this tool (which is anyway "experimental" and likely to be subject to issues at each change the good MS guys make with their updates). jaclaz Thank you for your help and your advice though !