I've encountered an issue where I am unable to delete, rename, or overwrite existing files on my computer, at least with certain extensions (.dll, .exe). This happens, for example, when I try to install an upgrade of a program -- the installer cannot finish the upgrade because it cannot replace the existing files. I also cannot delete the existing/old files manually, because I get a permissions error. Screenshots of two sample errors are attached -- these are from tonight when I tried to upgrade my MalwareBytes Anti-Malware. I use Avast Antivirus and it does not show any viruses. MalwareBytes also reports no malware. I am using the only account on my computer, the administrator account. I also ran a registry cleaner (CCleaner) and HiJackThis, but nothing seems amiss. The problem began a few weeks ago.
Oddly, if I hit "Retry" enough times in the installer -- maybe 10 or 15 times in a row -- it eventually overwrites the file. So, I AM able to install updates, but I have to continually press "Retry" over and over for each file.
Here's what I've tried so far: (1) Disabling UAC; (2) Running an installer as administrator; (3) Right-clicking individual files in Windows Explorer, selecting "Properties" -> Security (When I do this, all permissions appear proper -- System, Administrators, and Users all have full access).
Thanks for anyone's help!