One thing to check in case you will ever find yourself in such a situation where you are trying to start XMing process and nothing happens is the log file.
It seems you will have to check this log file and verify the permissions, especially if the user who is trying to start the XMing.exe process has rights to WRITE in the folder where the log file exists.
On a Windows 7 machine, you can access the log file by going to C:\Users\your_username\AppData\Local\Temp\Xming.0.log. Even if you see that the permissions look ok,
if XMing.exe doesn’t launch and you don’t see it minimized in your taskbar (default right bottom corner apps) you should rename/delete this Xming.0.log and try to start XMing again.
You can easily test if the log file is the problem if you right click using Shift on the XMing.exe and try to RUN AS another username. If it starts, then this might be the cause as
the log file can be corrupted.
There can also be other reasons, for example I found this after a few restarts combined with reinstallation after full cleanup and running Process Monitor which
reported that XMing.exe can’t write to this log but I checked permissions and all seemed fine. I decided that even if it looks OK, it’s still possible that the log file could be corrupted and surprise… as soon as I deleted the log, I could start the XMing process on the user’s session. I have to mention one more time that XMing.exe was running ok on other username as it was writing to different folders.
In case the error you are facing does not match mine or the details I provided, there is a possibility that you might be facing a different problem so feel free to contact me if you need my help and I will be happy to assist you.