[Samsung Galaxy Nexus] oscillik:
there is definitely an issue here related to the 2G radio.

Here is an extract from my log, after I enabled 2G Networks on my phone. You can quite clearly see buffer underruns immediately after changing to a 2G connection

11-20 00:21:26.097: I/Use2GOnlyCheckBoxPreference(403): set preferred network type=1
11-20 00:21:26.097: D/GsmUmtsOptions(403): preferenceTreeClick: return true
11-20 00:21:28.065: I/Use2GOnlyCheckBoxPreference(403): set preferred network type done
11-20 00:21:30.714: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:30.870: I/WindowManager(174): createSurface Window{425a37d0 Volume control paused=false}: DRAW NOW PENDING
11-20 00:21:30.933: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:30.956: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:31.011: D/dalvikvm(174): GC_CONCURRENT freed 1854K, 24% free 25950K/34119K, paused 3ms+6ms
11-20 00:21:31.730: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:31.862: D/dalvikvm(403): GC_CONCURRENT freed 1896K, 12% free 19843K/22535K, paused 2ms+5ms
11-20 00:21:31.886: D/SipKeepAlive(403): rport is the same: 42935
11-20 00:21:32.237: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:32.331: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:32.651: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:33.925: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:33.995: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:34.159: D/dalvikvm(659): GC_CONCURRENT freed 458K, 5% free 14452K/15111K, paused 2ms+2ms
11-20 00:21:35.425: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:35.425: I/InputReader(174): Dropping key up from device tuna-gpio-keypad because the key was not down. keyCode=25, scanCode=114
11-20 00:21:35.487: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:35.487: D/dalvikvm(174): GC_CONCURRENT freed 2723K, 27% free 25241K/34119K, paused 2ms+9ms
11-20 00:21:35.964: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:36.362: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:36.526: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:36.925: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:37.081: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:37.097: I/InputReader(174): Detected input event buffer overrun for device tuna-gpio-keypad.
11-20 00:21:44.745: D/dalvikvm(659): GC_CONCURRENT freed 455K, 5% free 14461K/15111K, paused 1ms+2ms
11-20 00:21:46.972: I/WindowManager(174): createSurface Window{41e0a1d8 Volume control paused=false}: DRAW NOW PENDING
11-20 00:21:58.909: I/WindowManager(174): createSurface Window{421413c8 Volume control paused=false}: DRAW NOW PENDING
11-20 00:22:00.105: D/dalvikvm(174): GC_FOR_ALLOC freed 1682K, 26% free 25569K/34119K, paused 68ms
11-20 00:22:00.206: D/dalvikvm(174): GC_CONCURRENT freed 686K, 27% free 24951K/34119K, paused 3ms+6ms
11-20 00:22:03.690: D/dalvikvm(12392): GC_CONCURRENT freed 463K, 4% free 15115K/15687K, paused 1ms+11ms
11-20 00:22:06.355: I/Use2GOnlyCheckBoxPreference(403): set preferred network type=0
11-20 00:22:06.362: D/GsmUmtsOptions(403): preferenceTreeClick: return true
11-20 00:22:07.847: I/Use2GOnlyCheckBoxPreference(403): set preferred network type done
11-20 00:22:12.105: V/BackupManagerService(174): Running a backup pass
11-20 00:22:12.105: V/BackupManagerService(174): clearing pending backups
11-20 00:22:12.105: V/PerformBackupTask(174): Beginning backup of 1 targets
11-20 00:22:12.214: D/PerformBackupTask(174): processOneBackup doBackup() on @pm@
11-20 00:22:12.222: V/BackupServiceBinder(174): doBackup() invoked
11-20 00:22:12.230: I/PerformBackupTask(174): no backup data written; not calling transport
11-20 00:22:12.230: D/PerformBackupTask(174): starting agent for backup of BackupRequest{pkg=com.android.providers.settings}
11-20 00:22:12.230: D/BackupManagerService(174): awaiting agent for ApplicationInfo{4198d440 com.android.providers.settings}
11-20 00:22:12.230: V/ActivityThread(174): handleCreateBackupAgent: CreateBackupAgentData{appInfo=ApplicationInfo{4198d440 com.android.providers.settings} backupAgent=com.android.providers.settings.SettingsBackupAgent mode=0}
11-20 00:22:12.230: D/SettingsBackupAgent(174): onCreate() invoked
11-20 00:22:12.230: V/ActivityThread(174): Initializing agent class com.android.providers.settings.SettingsBackupAgent
11-20 00:22:12.237: V/BackupServiceBinder(174): doBackup() invoked
11-20 00:22:12.237: D/BackupManagerService(174): agentConnected pkg=com.android.providers.settings agent=android.app.backup.BackupAgent$BackupServiceBinder@42234278
11-20 00:22:12.237: D/PerformBackupTask(174): processOneBackup doBackup() on com.android.providers.settings
11-20 00:22:12.261: V/ActivityThread(174): handleDestroyBackupAgent: CreateBackupAgentData{appInfo=ApplicationInfo{4198d440 com.android.providers.settings} backupAgent=com.android.providers.settings.SettingsBackupAgent mode=0}
11-20 00:22:12.698: I/PerformBackupTask(174): Backup pass finished.
11-20 00:22:28.894: I/power(174): *** set_screen_state 0
11-20 00:22:28.956: D/SurfaceFlinger(116): About to give-up screen, flinger = 0xf918
11-20 00:22:29.019: D/dalvikvm(174): JIT code cache reset in 10 ms (1048516 bytes 28/0)
11-20 00:22:29.034: D/dalvikvm(174): GC_CONCURRENT freed 1677K, 26% free 25299K/34119K, paused 7ms+19ms
11-20 00:22:29.097: V/TransportControlView(174): Create TCV com.android.internal.widget.TransportControlView@41825a88
11-20 00:22:29.230: D/dalvikvm(174): GC_EXPLICIT freed 131K, 24% free 26079K/34119K, paused 4ms+10ms
11-20 00:22:29.230: D/NfcService(416): EnableDisableDiscoveryTask: enable = false
11-20 00:22:29.237: D/PhoneStatusBar(248): disable: < expand icons alerts ticker system_info back home RECENT* clock >
11-20 00:22:29.261: I/WindowManager(174): createSurface Window{41b2fd28 Keyguard paused=false}: DRAW NOW PENDING
11-20 00:22:29.339: D/PhoneStatusBar(248): disable: < expand icons alerts ticker system_info BACK* HOME* RECENT CLOCK* >
11-20 00:22:29.425: D/dalvikvm(435): GC_CONCURRENT freed 1817K, 33% free 20017K/29511K, paused 4ms+5ms
11-20 00:22:36.558: D/SipKeepAlive(403): rport is the same: 53394
11-20 00:22:36.644: D/dalvikvm(403): GC_CONCURRENT freed 1840K, 12% free 19847K/22535K, paused 3ms+6ms
11-20 00:23:03.761: D/dalvikvm(12774): GC_CONCURRENT freed 500K, 4% free 15469K/16071K, paused 3ms+4ms

and here is the pastebin link http://pastebin.com/3ddK0G0v