A note regarding the drag and drop method. If you are using Windows Vista or later and you are also running Trainz as administrator, you may find that dragging and dropping does not work for you.
Shane
This makes no sense Shane, please elaborate on when you've seen this... the exact opposite of what would be expected. Dropping any dragged item removes all ambiguity and there is no reason for the Windows Software to try and access the MUIcache or RUNmui record to open the proper application. Especially when the application is already open! The only possible meaning I can give to your text is that the user hasn't registered himself as an administrator with full privileges and so is only running Trainz as an Administrator with the individual settings. THAT mode is particularly foolish on a PERSONAL COMPUTER... as it's a feature of a shared resource computer in a business. You avoid a lot of problems making sure your log-in identity is an Administrator in Windows.
To the OP,
on starting a download from the DLS -- this seems to work fine AFTER downloading something into an already open CM. Just look for something obsolete or outdated and do a quick download to prime the internet connection. In other words, it's
Safest to launch CM, download, then quit back to Windows desktop. This updates the Windows registry. Then relaunch CM or let the Browser launch CM for you. Then return to the webpage and launch there if you wish, cutting and pasting all those goodies is such a pain. This is my preferred method of searching... I like to see the pics and descriptions or don't usually grab an item (excepting by user or variant batches).
To the OP, the one thing I would suggest avoiding is running two Versions of Trainz at the same time because of TADdaemon; I do not have any sure negative experiences with this, but do think I may have launched once or twice and using the launcher, ended up using the database in the other Trainz version. This is nervous making, and such 'incidents' were relatively minor events, or I'd have a firmer memory of them... Having said that, I have however found myself doing so by accident and count myself lucky I didn't crash something. In sum, You want to avoid anything which might mix data bases.
THIS IS IN STARK contrast with running two CM's and/or Trainz runtime GUI's (i.e. Two CM's of the same version) which according to Jamesmoody is one reason they installed TADdaemon. Since this is designed in, it's safe meaning we can all set up looks at several different filters and even download while building a layout. This is because the Internet pipe is all handled through the local TADdaemon -- which is why things sometimes get slow--a likely unintended consequence. This change was primarily for multiplayer operation, but it does allow for other options. (I've had two CM's open at once, but haven't explored this voluntarily since I read the answer telling me this was a deliberate feature. I'd complained it was possible with just an careless double-click to launch, being a paranoid programmer type myself.) I've also clearly had Two CM's and two TADdaemon's active at once TS2009-SP4 and TS2010-SP2 which are version (3.3 and 3.2 respectively).
You can ensure which CM and database you are using by launching CM directly in the \bin subfolder or by setting up a shortcut to begin in that same folder which launches CM for you. I have a versions of Trainz (by individual Service Pack plateaus) from Trainz 2004-SP4 through TS12-SP1+hf3; actually more, as I keep a 'virgin' or 'clean' copy of major changes. If the upgrade took more than half an hour, you can bet I keep a virgin copy before importing data, and after. I manage which is which by keeping the launcher and CM shortcuts named clearly in a separate Trainz folder in my Start Menu. (Note taking content backwards to older Trainz versions is problematic.)
Further, if you download cdp's to a particular folder, perhaps because a third party site bundled them into a zip... or you got them from a friend or what ever, when you are running a CM for a particular build, it is in control, not the registry cpd file handler on record (You can see and change which Trainz has that by running Regedit, then use FIND to see '.cdp' and '.cdpa'.) so there is no ambiguity therein either, just import using the ALT-F dropdown menu again.
To the OP, TO address a point I didn't see covered... you can just import your already downloaded (or locally built and added content) from TS2010 to TS12 simply by importing the content using the [Alt]-[F] dropdown menu. // Frank