Freezing at Welcome to Windows popup

When I boot my pc freezes at the welcome to windows screen where it asks you to enter your user name and password. No error messages. Have rebooted and same problem.

There are a variety of new things going on.

Have just moved the pc from the UK to the US and this is the first time I have attempted to start it. (Have switched the power from 220 to 115)
Hooked up to a new monitor (new to the pc, very old monitor).
Was on a boat for 8 weeks, no idea what it went through.
Few other newcards removed/added before booting.

Have managed to get msgsrv32 not responing when I hit ctrl-alt-del and have to hit that again to get it to reboot.

Any thoughts on how to diagnose??

Many thanks!