Hi,

Please untick "tools>visual micro>automatic debugging" then try again

Thanks

As extra info, this is the complete compiler result in VS2013, with verbose messages on:
Compiling 'Timetest' for 'Arduino Mega w/ ATmega2560 (Mega 2560)'
Build folder: mega2560
Summary: Header=1 Prototypes=7 Imports=2
Additional Defines: VISUALMICRO_COMPILER_VER=1;
Architecture Tools: c:\Program Files (x86)\Arduino/hardware/tools/avr/bin/
GCC: 4.8.1
Sketchbook: file:///C:/Users/thijs..000/Documents/Arduino
Core Include Paths
Include Path 'c:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino'
Include Path 'c:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega'
Library Include Paths (2)
Include Path 'C:\Users\thijs..000\Documents\Arduino\libraries\Time'
Include Path 'c:\Program Files (x86)\Arduino\libraries\Keypad'
Platform Libraries Root Include Paths
Include Path 'c:\Program Files (x86)\Arduino\libraries'
Include Path 'c:\Program Files (x86)\Arduino\hardware\arduino\avr\libraries'
Include Path 'C:\Program Files (x86)\Visual Micro\Visual Micro for Arduino\Micro Platforms\default\debuggers'
Include Path 'C:\Users\thijs..000\Documents\Arduino\libraries'
"c:\Program Files (x86)\Arduino/hardware/tools/avr/bin/avr-g++" -c -g -Os -Wall -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD -mmcu=atmega2560 -DF_CPU=16000000L -DARDUINO=158 -DARDUINO_AVR_MEGA2560 -DARDUINO_ARCH_AVR -I"c:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino" -I"c:\Program Files (x86)\Arduino\hardware\arduino\avr\variants\mega" -I"C:\Users\thijs..000\Documents\Arduino\libraries\Time" -I"c:\Program Files (x86)\Arduino\libraries\Keypad" -I"c:\Program Files (x86)\Arduino\libraries" -I"c:\Program Files (x86)\Arduino\hardware\arduino\avr\libraries" -I"C:\Program Files (x86)\Visual Micro\Visual Micro for Arduino\Micro Platforms\default\debuggers" -I"C:\Users\thijs..000\Documents\Arduino\libraries" 0\Timetest.cpp" -o 0\Timetest.cpp.o" -DVISUALMICRO_COMPILER_VER=1
"c:\Program Files (x86)\Arduino/hardware/tools/avr/bin/avr-gcc" -w -Os -Wl,--gc-sections -mmcu=atmega2560 -o 0/Timetest.elf" 0\Timetest.cpp.o" 0\Time\DateStrings.cpp.o" 0\Time\Time.cpp.o" 0\Keypad\Keypad.cpp.o" 0\Keypad\utility\Key.cpp.o" 0/core.a" 560" -lm
crtm2560.o*.init9+0x0): undefined reference to `main'
Timetest.cpp.o:In function `__static_initialization_and_destruction_0'
Timetest.ino:String(char const*)'
Timetest.ino:~String()'
collect2*:error: ld returned 1 exit status
Error creating .elf


maybe this shines some light?

Hi Tim,

I was busy getting your information and proceeded on your last action: Clean project and then rebuild.

That did the trick, it's all working again..

Thanks a lot!!!