Just remove all traces of litecoin from your PC and try again....IE: Everything in %APPDATA% relating to Litecoin (folders and all) and then remove your other (main program) Litecoin folder- then download and re-install...If that doesn't work try on another PC as it's obviously system related and not Litecoin related....
Hi this OP, since last time, i experimented a bit.
When i install Litecoin on C:, it doesn't create wallet.dat in appdata, and my wallet is locked whether it is there or not.
Installing Litecoin on D: gives me a new wallet, and creates a wallet.dat in appdata.
When im installed on D: and i delete wallet.dat from C:'s appdata, my wallet actually is lost, like it's supposed to. Then on next litecoin start it creates a new random wallet.
But no matter how i install it on the C:, it won't create a wallet.dat