Excellent, thanks for the great feedback and seeing it through. I'll try re-producing what you had. Best of luck with everything

Another note... If I right-click "File" in my code and select "Goto Implementation (Alt+G), the file (C:\Arduino\arduino-1.0.5-r2\libraries\SD\SD.h) opens up just fine.  So my guess it's being "seen" by the IDE, and not the compiler somehow.

Thanks
--- Output ---
Compiling 'epicSDCardFunctions' for 'Arduino Mega or Mega 2560 w/ ATmega2560 (Mega 2560)'
Build folder: s/mega_atmega2560
SketchLibFolders
vr\lib\gcc\avr\4.3.2\include\;
Summary: Header=1 Prototypes=15 Imports=4
Additional Defines: VISUALMICRO_COMPILER_VER=1;
Architecture Tools: C:\Arduino\arduino-1.5.6-r2\hardware\tools\avr\bin\
GCC: 4.3.2
Sketchbook: file:///C:/Users/Christos/Documents/Arduino
"C:\Arduino\arduino-1.5.6-r2\hardware\tools\avr\bin\avr-g++" -c -g -Os -w -fno-exceptions -ffunction-sections -fdata-sections -MMD -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=150 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR -I"C:\Arduino\arduino-1.5.6-r2\hardware\arduino\avr\cores\arduino" -I"C:\Arduino\arduino-1.5.6-r2\hardware\arduino\avr\variants\mega" -I"C:\Arduino\arduino-1.5.6-r2\hardware\arduino\avr\libraries\SPI" atmega2560\epicSDCardFunctions.cpp" -o atmega2560\epicSDCardFunctions.cpp.o" -DVISUALMICRO_COMPILER_VER=1
epicSDCardFunctions.ino:20: error: 'File' does not name a type
epicSDCardFunctions.ino:21: error: 'File' was not declared in this scope
epicSDCardFunctions.ino:22: error: 'File' was not declared in this scope
epicSDCardFunctions.ino:23: error: 'File' was not declared in this scope
epicSDCardFunctions.ino:24: error: variable or field 'loadMimicFile' declared void
epicSDCardFunctions.ino:24: error: 'File' was not declared in this scope
epicSDCardFunctions.ino:29: error: variable or field 'loadMimicAddressesFromSD' declared void
epicSDCardFunctions.ino:29: error: 'File' was not declared in this scope
epicSDCardFunctions.ino:32: error: 'File' does not name a type
epicSDCardFunctions.ino:In function 'void setup()'
epicSDCardFunctions.ino:43: error: 'mimicFile' was not declared in this scope
epicSDCardFunctions.ino:43: error: 'FILE_WRITE' was not declared in this scope
epicSDCardFunctions.ino:43: error: 'openMimicFile' was not declared in this scope
epicSDCardFunctions.ino:49: error: 'loadMimicAddressesFromSD' was not declared in this scope
epicSDCardFunctions.ino:51: error: 'closeMimicFile' cannot be used as a function
epicSDCardFunctions.ino:At global scope
epicSDCardFunctions.ino:60: error: 'File' does not name a type
epicSDCardFunctions.ino:118: error: redefinition of 'bool closeMimicFile'
epicSDCardFunctions.ino:21: error: 'bool closeMimicFile' previously defined here
epicSDCardFunctions.ino:118: error: 'File' was not declared in this scope
epicSDCardFunctions.ino:130: error: redefinition of 'bool clearMimicFile'
epicSDCardFunctions.ino:22: error: 'bool clearMimicFile' previously defined here
epicSDCardFunctions.ino:130: error: 'File' was not declared in this scope
Error compiling

Thanks again, I'll try that.

I have a Yun, too, which is why I am using 1.5.6-r2.  I have a bunch of different Arduinos.  They are nice for quick and dirty prototyping and general tomfoolery.

Did you guys ever resolve the following bug?  It's very annoying.

"System.Exception: Visual Micro: Unable to save new program settings file ...\Visual Micro\Compile.vmps.xml ---> 

System.IO.IOException: The requested operation cannot be performed on a file with a user-mapped section open.

Thanks