Ok... I've seen this one before...
Whatever the instructions tell you
DO NOT copy outsider files to the Pelles C directories. Just don't do it.
Instead set them up in their own folder in your project space and add the folders to your Project Options on a project by project basis.
( Project->Project Options->Folders )
Now since it seems you've got a mangled installation on your hands...
- Uninstall Pelles C.
- Open explorer and go to c:\Program Files (x86) and delete the Pelles C folder if it's still there
- Now go to C:\Program Files and delete the Pelles C folder if you find one there as well.
- Press and hold the windows logo key and type an R, you should see a run dialog... In the Run dialog type REGEDIT and click OK... in RegEdit path to HKEY_CURRENT_USER\Software... now locate the branch named "Pelle Orinius"... right click on it and delete it.
If you don't already have Pelles C version 7.0 go and
download the 64 bit version (because you're on a 64 bit os) and install it into the default location (C:\Program Files\PellesC). You will need to rebuild the browse info (it will prompt you) and you should go into the options panels and set everything up to your liking ...
Since the SDL libraries are 32 bits, you have some choices here... Use them only in 32 bit projects (P.C x64 creates either 32 or 64 bit projects) -or- recompile them into both 32 and 64 bit versions so you can use them in either 32 or 64 bit projects. In either case --except for addins and wizards-- don't be putting the files into any folder inside the Pelles C insallation. As I said above, set them up in their own folder(s) and add the folders to your project options on a project by project basis.
For the UAC problem... find POIDE64.EXE in your PellesC\bin folder, right click select ->Properties->Compatibility and check "Run as Administrator" --or-- Control Panel->Action Center->Change User Account Control Settings and disable the UAC warnings entirely.