If you don't have much time yet would like to know what the most common sources of errors are in your System event log, try this line:
Get-EventLog -LogName System -EntryType Error, Warning | Group-Object -Property Source | Sort-Object -Property Count -Descending
Once you found a source that caused a lot of errors (or warnings), this line would provide you with the error details:
# change this variable to the name of the source you want # to explore: $source = 'Schannel' Get-EventLog -LogName System -Source $source | Out-GridView