I kinda ran into that issue before, but the tdm_update.exe doesn't seem to behave properly: it just downloads a file of size 1.5 MB, then asks to restart and repeats this again. I then did the following (now it works, but I don't know which of these steps were necessary):
- I deleated all files in the darkmod directory
- I downloaded a new version of the updater
- When the button asking for a Restart appears, I go to the directory instead and run the file _tdm_update.exe (instead tdm_update.exe)
I just thought I let you know about this.