I have been having the same problem, Here's my log.
[16:59:58] [sEVERE]------------------------------------------
[16:59:58] [sEVERE]Launcher is starting....
[16:59:58] [sEVERE]Launcher Build: '1.0.1.3'
[16:59:58] [sEVERE]Allocated 910.25 Mb of RAM
[16:59:58] [sEVERE]Java VM: '1.7.0_04-b22'
[16:59:58] [sEVERE]OS Version: '6.1'
[16:59:58] [sEVERE]Is 64-bit: 'true'
[17:00:08] [sEVERE]java.lang.NullPointerException
[17:00:08] [sEVERE]at org.spoutcraft.launcher.MirrorUtils.getMirrorUrl(MirrorUtils.java:30)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.MirrorUtils.getMirrorUrl(MirrorUtils.java:76)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.MD5Utils.updateMD5Cache(MD5Utils.java:71)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.gui.LoginForm.loadLauncherData(LoginForm.java:360)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.gui.LoginForm.<init>(LoginForm.java:133)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.Main.main(Main.java:194)
[17:00:08] [sEVERE]All mirrors failed, reverting to default
[17:00:08] [sEVERE]java.lang.NullPointerException
[17:00:08] [sEVERE]at org.spoutcraft.launcher.MirrorUtils.getMirrorUrl(MirrorUtils.java:30)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.MirrorUtils.getMirrorUrl(MirrorUtils.java:76)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.YmlUtils.downloadYmlFile(YmlUtils.java:45)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.YmlUtils.downloadRelativeYmlFile(YmlUtils.java:24)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.modpacks.ModPackListYML.updateModPacksYMLCache(ModPackListYML.java:82)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.modpacks.ModPackListYML.getConfig(ModPackListYML.java:72)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.modpacks.ModPackListYML.getModPacks(ModPackListYML.java:108)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.modpacks.ModPackListYML.<clinit>(ModPackListYML.java:60)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.gui.LoginForm.loadLauncherData(LoginForm.java:361)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.gui.LoginForm.<init>(LoginForm.java:133)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.Main.main(Main.java:194)
[17:00:08] [sEVERE]All mirrors failed, reverting to default
[17:00:08] [sEVERE]Exception in thread "main"
[17:00:08] [sEVERE]java.lang.NullPointerException
[17:00:08] [sEVERE]at org.spoutcraft.launcher.modpacks.ModPackListYML.getAllModPackResources(ModPackListYML.java:186)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.gui.LoginForm.loadLauncherData(LoginForm.java:363)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.gui.LoginForm.<init>(LoginForm.java:133)
[17:00:08] [sEVERE]at org.spoutcraft.launcher.Main.main(Main.java:194)