I should have mentioned this, also, but IE will not run in "safe" mode, either. Likewise, running Inetcpl.cpl results in a "Windows host process (Rundll32) has stopped working." with a "Faulting application rundll32.exe, version 6.0.6000.16386, time stamp 0x4549b0e1, faulting module Secur32.dll, version 6.0.6002.18541, time stamp 0x4ec3e394, exception code 0xc0000005, fault offset 0x000021dc, process id 0x2d88, application start time 0x01cfa27ec7b59960." in the Event log. I have also done a full virus scan using Malwarebytes and the box is clean.
I could also reinstall Vista but it's more fun and educational to try to figure-out what's going on!