....so Spybot found and tried to remove some malware (Win32.Agent.px & Win32.Zbot).....couldn't fully remove one of them and asked if it could attemp on the next reboot.
During the next reboot Spybot ran and succesfully(?) removed the remaining malware.
Since then when the computer boots, I log in as normal and the computer hangs (just showing the wallpaper).
I can Ctrl-Alt-Del to the task manager and Run explorer.exe and everything seems normal. But I have to manually run explorer.exe every time I re-boot.

Is this something to do with Spybot temporarily disabling explorer.exe while it re-ran on boot-up ?