Could it be that you have set UserVars.ESXiShellTimeOut to a very low value ?
You can check with
Get-VMHost|SelectName,
@{N="ESXiShellTimeout";E={Get-VMHostAdvancedConfiguration-VMHost$_-NameUserVars.ESXiShellTimeOut|Select-ExpandPropertyValues}}
A value of 0 means there is no timeout.