Symantec Client Security 3.1 - SAV (Symantec AntiVirus) 10 will
immediately quarantine RAdmin.exe so that you can no longer use it via it's
"File System Auto-Protect". Turn of the "File System Auto-Protect" and
then go into the quarantined files and undo the action.
Solution
Open up SAV - Symantec AntiVirus.
Click on "Configure"
Click "File System Auto-Protect"
Allow All - Uncheck "Enable Auto-Protect (Enabled).
Click "OK"
Exit SAV
Reinstall RAdmin (FYI: your server setting will be preserved).
(Reboot will be required by RAdmin install).