I dont think it is Reshade 3.03 that is the faulty one. Postive negatives happens now and then. I just share it for future reference. I think my antivirus reaction of trying to run the setup tool was a anomaly. But I thought I tell it here in case someone finds themselves with a installiton problem. No worries
1. Right click on the green panda virus
2. Click Panda antivirus
3. Under the green compass there is a "Files in quarantine", it should probaly say "Files in quarantine:1". Click it
4. Click view detals
5. Press recover file, Make damn sure it is "Reshade_Setup_3.0.3.exe"
6. After recovery the virus software has learnt that is nothing fishy with Reshade, as long you download it at "reshade.me". You have no reasons to fear
EDIT note: This has never happend before in any reshade version, I highly suspect something fishy is going with my computer
This usually goes away after a few days. 3.0.3 was just released and as such the executable file is new and not used by many antivirus users yet and some antivirus software will flag it locally until it's more widespread. Avast is another one that did this if enabled in the options (though it might be resolved now, I contacted their support and they said it'll be fixed).