When you create a profile that specifies a game directory that does not exist the following IOException is thrown when trying to start a game:

java.io.IOException: Cannot run program "C:\Program Files\Java\jre7\bin\javaw.exe" (in directory "C:\Games (x86)\Minecraft\Dev"): CreateProcess error=267, The directory name is invalid
at java.lang.ProcessBuilder.start(Unknown Source)
at net.minecraft.launcher.process.JavaProcessLauncher.start(JavaProcessLauncher.java:25)
at net.minecraft.launcher.GameLauncher.launchGame(GameLauncher.java:218)
at net.minecraft.launcher.GameLauncher.onDownloadJobFinished(GameLauncher.java:394)
at net.minecraft.launcher.updater.download.DownloadJob.popAndDownload(DownloadJob.java:95)
at net.minecraft.launcher.updater.download.DownloadJob.access$000(DownloadJob.java:10)
at net.minecraft.launcher.updater.download.DownloadJob$1.run(DownloadJob.java:65)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: CreateProcess error=267, The directory name is invalid
at java.lang.ProcessImpl.create(Native Method)
at java.lang.ProcessImpl.<init>(Unknown Source)
at java.lang.ProcessImpl.start(Unknown Source)
... 13 more