Here is a list I'm compiling of Client troubleshooting issues and resolutions.
Idea and format taken from SCCM 2012 Client Troubleshooting
If Updates won't install
WUAHandler.log 80004005
1. Delete C:\Windows\System32\GroupPolicy\Machine\Registry.pol
2. Run Software Updates Deployment Evaluation Cycle
WUAHandler.log 8007000d Cause: Pointing to old update server URL
1. Delete C:\Windows\System32\GroupPolicy\Machine\Registry.pol
2. Run Software Updates Deployment Evaluation Cycle
WUAHandler.log 80072ee2
1. Run Software Updates Deployment Evaluation Cycle while computer has good connectivity
WUAHandler.log 80072efe
1. Run Software Updates Deployment Evaluation Cycle while computer has good connectivity
WUAHandler.log 80080005
1. Reboot computer
2. Verify WUAUSERV service is running
3. Run Software Updates Deployment Evaluation Cycle
WUAHandler.log c80003f3
1. Launch PowerShell
2. Stop-Service wuauserv
3. Remove-Item "C:\Windows\SoftwareDistribution" -Force
4. Start-Service wuaserv
5. Run Software Updates Deployment Evaluation Cycle
WUAHandler.log 80244022
WUAHandler.log 8024002D (-2145124307)
1. Uninstall and Reinstall CM client
WUAHandler.log 87D00605 (-2016410107)
1. Uninstall and Reinstall CM client
If PXE won't boot
Windows Boot Manager c0000001
Problem: Boot failure right after boot.sdi message. Error 0xc0000001. "A required device isn't connected or can't be accessed."
1. Reduce RamDiskTFTPBlockSize but keep in 1024 increments
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\DP\RamDiskTFTPBlockSize
Source: http://tech.cellfi.sh/journal/2013/4/28/windows-pe-sccm-pxe-boot-problems-bootsdi
Additional Information: How Booting into a Boot Image Works
