If you already have cygwin installed on your computer, you might get an error like this when you try to compile a sketch in Arduino:
6 [main] ? (3512) C:\Dev\arduino-0006\tools\avr\bin\avr-gcc.exe: *** fatal error - C:\Dev\arduino-0006\tools\avr\bin\avr-gcc.exe: *** system shared memory version mismatch detected - 0x75BE0084/0x75BE009C.
This problem is probably due to using incompatible versions of the cygwin DLL.
To check wether this is the issue, search for
cygwin1.dll using the Windows
Start->Find/Search facility and delete all but the most recent version. The most recent version should reside in
x:\cygwin\bin, where 'x' is the drive on which you have installed the cygwin distribution. Rebooting is also suggested if you are unable to find another cygwin DLL.
If so, first make sure that you don't have cygwin running when you use Arduino. If that doesn't help, you can try deleting
cygwin1.dll from the Arduino directory and replacing it with the
cygwin1.dll from your existing cygwin install (probably in
Thanks to karlcswanson for the suggestion.