This underrated little gem has a few glitches here and there, but I have posted the answers to all of the most common questions I am seeing, so please read before posting a new topic as this may answer your question. I recently played through it again and the game brought to me the magic it did the first time around in 2006, so I've decided to offer some support as I used to maintain a fanatical infatuation with this game to the point where I could probably remake it blindfolded.
COMMON BUGS/GLITCHES (This contains spoilers! Read at your own risk.):
(Q) The game crashes randomly.
(A) Tell it not to drink and drive, although in all seriousness, this does happen from time to time. Also note that DCOTE does not allow alt-tabbing very well. Replay to the segment of the game where the crash occurred, and it will either occur again (see below) or it won't. Be sure to close any unnecessary programs that hog RAM, and are using processes (ie ensure no virus scans are running, etc).
(Q) I'm stuck in a hotel with a group of armed fishmen trying to gun me down, I have no weapons, how can I defend myself?
(A) Move as quickly as you can, block doors, et cetera. Until you reach the Jailhouse, you will not be acquiring any weapons in the game.
(Q) I cannot open one of the safes
(A) Try starting off the first number by rotating the dial in the opposite direction. So if the safe combination is 1984, you could try rotating to the right to 1, then to the left until you reach 9, et cetera, or you begin by rotating to the left to 1, then right to 9, and so on.
(Q) I can't push the bookcase in front of the safe in the jailhouse
(A) Instead of moving it in one movement, tap your "forward" key so you move it a tiny bit at a time. You may do this as fast as you please, however moving it in one large movement will cause the game to crash for certain computer setups.
(Q) I'm in a chamber under the refinery, I hear a laser but I don't see one when I have to unlock the red gem.
(A) This is a common bug found on newer machines. I will post a video segment and edit this post to include it here when I do my video walk/playthrough. You must push the pillar in the direction you came from for about 2.5 seconds.
(Q) I'm on the Cutter Urania, and I can't see the blue lights on the horizon
(A) This is a common software rendering issue on modern machines. Download the software rendering DLL http://www.megaupload.com/?d=OEYQS87A, and place it in your "Engine" folder found in C:\program files\Bethesda Softworks\Call of Cthulhu - Dark Corners of the Earth\Engine. This should enable you to see the lights.
(Q) I'm trying to escape the underwater tunnels and I keep getting crushed by rocks as I'm running through them, what can I do?
(A) You must cut every corner you can when running, move as fast as you possibly can. Changing resolutions and graphics options can also alter the way in which the games timer works, so you could try lowering your resolution to the lowest possible setting to allow for maximum smoothness, which will allow you to run as fast as possible.
(Q) I am taking control of a Deep One in a chamber, and I cannot swat the switches on the back of the statues.
(A) Reload your last save. This problem is caused when the fact you have left Jacks body does not register with the game. You are then technically free to roam as a deep one but you cannot do anything except fight other deep ones.
(Q) I have tried some or all of the above solutions, and some or all didn't work, what can I do?
(A) An unofficial fan-made patch was released called "svckleads DCOTE Patch". The patch can be acquired at http://svcklead.com/dcotepatch.exe. The patch can be used to modify various factors of the game, such as running speed, jumping height, et cetera. In order to keep the balance of the game as original as possible, I suggest modifying the walking speed from "380" to "560", as the game did once have a sprint feature which used the value of 560, so as long as you don't mind sprinting everywhere rather than a slow jog, this should help immensely. The jump value can also be changed from 590 to 650 and I have found this to be the most optimal setup which does not ruin the games balance in any way.
The patch is an unofficial tool, and neither myself, nor Bethesda Softworks take any responsibilities for your use of the patch. Use the patch at your own risk. Always remember to backup your original Cocwinmain32.exe as using the XML editor in the patch can break your EXE. I can also provide a savegame for the start of each chapter, or I can provide one just past a particular trouble point if you are struggling.
If you're still having problems, contact me. I still get email notifications when someone PM's me. Sadly a lot of the community spirit and tech support threads went when the forums shifted from CallofCthulhu.com to Bethesdas' site, however I am here to provide support because I believe everyone should give this game a fair go, given the rough development history, I don't blame it for having a few bugs (At one point a bulldozer went through the office walls of Headfirst Interactive) and had it not been for a few developers who stayed back late most likely downing copious cups of joe and sugar snacks, we likely wouldn't have even seen a PC port.
Now buckle up and enjoy the most immersive game you're likely to play in a while.
-James (or Ray)