This is for others who might have the same issue and not understand how to fix it. It might be already documented elsewhere, but I can't find it right now.
On my Windows XP SP3 system, the as downloaded system Portable_Ubuntu_TRES.exe did not work.
The displayed error was a pop-up containing "A fatal error has occurred and Cygwin/X will now exit."
Checking the log revealed that the file system does not support files starting with ".", and that the lock file name was such a file "/tmp/.X0-lock".
I had to make the below edit to … \Portable_Ubuntu_TRES\bin\run_X.bat
XWin.exe :0 -ac -notrayicon -multiwindow -dpi 100
XWin.exe :0 -ac -notrayicon -nolock -multiwindow -dpi 100
A more flexible fix would be to add a test to run_X.bat for the ability of the filesystem to make a ".test" file, checking with "if exist" and choose the command based on the results.
I downloaded portable unbuntu tres and tried to run it on WIndows 7. I got the same error message as you did, so I tried to add the "-nolock" on the call to XWin, but it still seems to be crashing at the same point.
I get basically the same error, except that the command line in it is the new one.
Any clue why it is still not working like this ?
Please refer to my article in Voofie/Ubuntu:
Fixing Cygwin/X error in Portable Ubuntu Remix TRES
In the article, you can find a file to download and fix the error in TRES.
I had a similar problem when i first tried Portable_Ubuntu_TRES, the Cygwin/Xserver crashed and my /var/log/XWin.0.log had the following error listing at ists end:
2010-11-03 23:08:52 (II) GLX: Initialized DRISWRAST GL provider for screen 0
2010-11-03 23:08:52 [dix] Could not init font path element /usr/share/fonts/misc/, removing from list!
2010-11-03 23:08:52 [dix] Could not init font path element /usr/share/fonts/TTF/, removing from list!
2010-11-03 23:08:52 [dix] Could not init font path element /usr/share/fonts/OTF/, removing from list!
2010-11-03 23:08:52 [dix] Could not init font path element /usr/share/fonts/Type1/, removing from list!
2010-11-03 23:08:52 [dix] Could not init font path element /usr/share/fonts/100dpi/, removing from list!
2010-11-03 23:08:52 [dix] Could not init font path element /usr/share/fonts/75dpi/, removing from list!
2010-11-03 23:08:53 (EE) XKB: Could not invoke xkbcomp
2010-11-03 23:08:53 (EE) XKB: Couldn't compile keymap
2010-11-03 23:08:53 XKB: Failed to compile keymap
2010-11-03 23:08:53 Keyboard initialization failed. This could be a missing or incorrect setup of xkeyboard-config.
Fatal server error:
2010-11-03 23:08:53 Failed to activate core devices.
My solution was moving the Portable_Ubuntu_TRES-Folder to the root of the hardrive, p.e. X:\, 'cause cygwin had often problems with difference of allowed characters and length of the path between win and un*x enviroment and it works.