When launching / starting Toad for Oracle, the following error messages are received.
"No mapping for the Unicode character exists in the target multi-byte code page"
"A critical error has occurred while trying to load C:\Users\username\AppData\Roaming\Quest Software\Toad for Oracle\12.12\User Files\Toad.ini.
Also found that the last couple of lines of the Toad.ini have changed and contain unusual characters. Manually changing the last line of the Toad.ini file back to VARCHAR=FALSE allows Toad to launch, but the problem quickly comes back.
This issue can also occur in v13.3 and v14.