So apparently the "ENTER" after run-mspaint was the problem. Strange.
Anyway, try it out! its good fun!
//Wallpaper Prank, modified by DW for use on the digispark
#include "DigiKeyboard.h"
void setup() {
pinMode(1, OUTPUT); //LED on Model A
}
void loop() {
DigiKeyboard.update();
DigiKeyboard.sendKeyStroke(0);
DigiKeyboard.delay(3000);
DigiKeyboard.sendKeyStroke(KEY_M, MOD_GUI_LEFT); //minimize all windows
DigiKeyboard.delay(1000);
DigiKeyboard.sendKeyStroke(KEY_PrintScreen); //prntscr
DigiKeyboard.delay(50);
DigiKeyboard.sendKeyStroke(KEY_F10, MOD_SHIFT_LEFT); //Open Menu
DigiKeyboard.delay(200);
DigiKeyboard.sendKeyStroke(KEY_V);
DigiKeyboard.delay(50);
DigiKeyboard.sendKeyStroke(KEY_D);
DigiKeyboard.delay(500);
DigiKeyboard.sendKeyStroke(KEY_R, MOD_GUI_LEFT); //run
DigiKeyboard.delay(100);
DigiKeyboard.println("mspaint");
DigiKeyboard.delay(1200);
DigiKeyboard.sendKeyStroke(KEY_V, MOD_CONTROL_LEFT); //paste
DigiKeyboard.delay(500);
DigiKeyboard.sendKeyStroke(KEY_S, MOD_CONTROL_LEFT); //save
DigiKeyboard.delay(500);
DigiKeyboard.println("%userprofile%\\a.bmp"); //save in users folder
DigiKeyboard.delay(500);
DigiKeyboard.sendKeyStroke(KEY_F, MOD_ALT_LEFT); //file
DigiKeyboard.delay(500);
DigiKeyboard.sendKeyStroke(KEY_K); //set as desktop
DigiKeyboard.delay(100);
DigiKeyboard.sendKeyStroke(KEY_T); //tile
DigiKeyboard.delay(1000);
DigiKeyboard.sendKeyStroke(KEY_F4, MOD_ALT_LEFT); //close paint
DigiKeyboard.delay(300);
DigiKeyboard.sendKeyStroke(KEY_M, MOD_GUI_LEFT | MOD_SHIFT_LEFT); //back to desktop as it was
digitalWrite(1, HIGH); //turn on led when program finishes
DigiKeyboard.delay(90000);
digitalWrite(1, LOW);
DigiKeyboard.delay(5000);
}