Access denied when deploying a solution in SharePoint

There are many posts about this issue but none applied to my situation. I was trying to deploy a solution that I know works, and it kept giving me "Access denied":

This was on a Windows 2008R2 machine and the user account I was using was an admin on everything. Turned out it's the annoying UAC issue again. Once I right clicked IE and did Run As Administrator, browsed to the Central Admin, and tried deploying the solution again, it worked successfully. UAC was preventing the changes to GAC, and maybe some other things too.