Ever since Minecraft 1.7.2 got released and the launcher updated to 1.2.8, I am often experienced logging in issues, sometimes it also gives error while doing "resources" job.
When I cannot login, I have to play offline. Luckily, I can still launch the game.

Here is the log:

[19:36:36 INFO]: Launcher 1.2.8 (through bootstrap 5) started on windows...
[19:36:36 INFO]: Current time is Oct 28, 2013 7:36:36 PM
[19:36:36 INFO]: System.getProperty('os.name') == 'Windows 8'
[19:36:36 INFO]: System.getProperty('os.version') == '6.2'
[19:36:36 INFO]: System.getProperty('os.arch') == 'amd64'
[19:36:36 INFO]: System.getProperty('java.version') == '1.7.0_45'
[19:36:36 INFO]: System.getProperty('java.vendor') == 'Oracle Corporation'
[19:36:36 INFO]: System.getProperty('sun.arch.data.model') == '64'
[19:36:36 INFO]: Refreshing local version list...
[19:36:36 INFO]: Refreshing remote version list...
[19:36:38 INFO]: Refresh complete.
[19:36:38 INFO]: Loaded 1 profile(s); selected 'pra_viilon'
[19:36:38 INFO]: Refreshing auth...
[19:36:38 INFO]: Logging in with access token
[19:36:53 ERROR]: Exception whilst logging into profile
com.mojang.authlib.exceptions.AuthenticationUnavailableException: Cannot contact authentication server
at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:58) ~[launcher.jar:?]
at com.mojang.authlib.yggdrasil.YggdrasilUserAuthentication.logInWithToken(YggdrasilUserAuthentication.java:107) ~[launcher.jar:?]
at com.mojang.authlib.yggdrasil.YggdrasilUserAuthentication.logIn(YggdrasilUserAuthentication.java:55) ~[launcher.jar:?]
at net.minecraft.launcher.Launcher.ensureLoggedIn(Launcher.java:222) [launcher.jar:?]
at net.minecraft.launcher.Launcher$2.run(Launcher.java:191) [launcher.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.7.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.7.0_45]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:1.7.0_45]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:1.7.0_45]
at java.lang.Thread.run(Unknown Source) [?:1.7.0_45]
Caused by: java.net.SocketTimeoutException: connect timed out
at java.net.TwoStacksPlainSocketImpl.socketConnect(Native Method) ~[?:1.7.0_45]
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source) ~[?:1.7.0_45]
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source) ~[?:1.7.0_45]
at java.net.AbstractPlainSocketImpl.connect(Unknown Source) ~[?:1.7.0_45]
at java.net.PlainSocketImpl.connect(Unknown Source) ~[?:1.7.0_45]
at java.net.SocksSocketImpl.connect(Unknown Source) ~[?:1.7.0_45]
at java.net.Socket.connect(Unknown Source) ~[?:1.7.0_45]
at sun.security.ssl.SSLSocketImpl.connect(Unknown Source) ~[?:1.7.0_45]
at sun.net.NetworkClient.doConnect(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.http.HttpClient.openServer(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.http.HttpClient.openServer(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.protocol.https.HttpsClient.<init>(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.protocol.https.HttpsClient.New(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown Source) ~[?:1.7.0_45]
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(Unknown Source) ~[?:1.7.0_45]
at com.mojang.authlib.HttpAuthenticationService.performPostRequest(HttpAuthenticationService.java:73) ~[launcher.jar:?]
at com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService.makeRequest(YggdrasilAuthenticationService.java:41) ~[launcher.jar:?]
... 9 more
[19:36:58 INFO]: Download job 'Resources' skipped as there are no files to download
[19:36:58 INFO]: Job 'Resources' finished successfully