שלום Well, that seems odd. I know I had no problem installing on my install on Win8.1 Pro x64. Although it might be that it does not automatically install symbols unless you donate and unlock that (I dont know for sure, I donated as soon as I could) What does the debug.log say in the install location? Hi, This is what i get in the log file: [2014-10-10 10:58:30][0x1348:0x1394] Installing DWM hook...[2014-10-10 10:58:30][0x1348:0x1394] User: SYSTEM[2014-10-10 10:58:30][0x1348:0x1394] Module: C:\AeroGlass\dwmglass.dll[2014-10-10 10:58:30][0xC20:0x10D0] Donation key not loaded (2 - The system cannot find the file specified.)[2014-10-10 10:58:30][0xC20:0x10D0] Machine ID: AC3GJFLMLUYTTL755MITLTE34MYL3BIVNZLIUKFI6L3CMAPA[2014-10-10 10:58:30][0xC20:0x10D0] Loading settings (flags = 0x1) from HKEY 0x0000000000000000 for session #2[2014-10-10 10:58:30][0xC20:0x10D0] Aero Glass for Win8.1 v1.2.5 x64 correctly loaded (C:\AeroGlass\dwmglass.dll).[2014-10-10 10:58:30][0xC20:0xCF0] dwmcore.dll version 6.3.9600.17200[2014-10-10 10:58:30][0xC20:0xCF0] udwm.dll version 6.3.9600.17284[2014-10-10 10:58:30][0xC20:0xCF0] DWM incompatibility error 0x4. שלום Ok, so you dont have the donate key and therefore need to manually download symbols in order for the transparency to work. I dont have a guide off the top of my head because I never needed to do this... maybe give me a second. [edit] Dont really have time to find how to do it for you but I am sure you can find it easy enough. It's not because they didn't donate. It would still install and just display a watermark, that error sounds more like it has to do with the windows version I would think? EDIT: I see trungdinh1890 mentioned the problem might be after a new windows update, I'll hold off on updating then until bigmuscle looks into it.