Thief (in-game bugs)

So it's been almost a year since I last played Thief. I have yet to complete it and I was last playing through the longest mission that I kept replaying in attempt to get Undetected. But now that I put the disc in there's a couple of problems. I will list the lesser of two evils first which I discovered after deciding to just go ahead and play: I can't do stealth takedowns. No matter how close the guard is to me as I'm perched above him, I'm not given the option to attack. I looked up this glitch online and there's no satisfactory solution. You either have a game that works or you don't. The same is true for the bigger problem: all three of my save slots say Chapter 2 Dust to Dust and display today's date. And this isn't a case of replaying the mission, the game has mysteriously started me over near the beginning. Now I last recall having two save files: Master-Custom and Rogue-Custom. Now they all say the latter. I no longer have my wrench or my cutter and I'm still peeved that I can't do atds.

Has anything like this happened to anyone else?

New problem: I had deleted two of the redundant files and continued to play the Rogue-Custom. But I decided maybe trying a new game in a different difficulty would help me figure why I cpuldn't do takedowns. I went to an empty slot and hit new game. But I changed my mind about starting it up and opted to just go back to the file I was playing in. Now that one is deleted too. F--k Thief. F--k Square Enix. Why the hell do I bother with this?