HP 1600 Check Paper and Check Print Cartridges lights flashing

I have an HP 1600/CM which starts to print and then almost immediately stops
with the Check Paper and Check Print Cartridges lights flashing. Power
off/on and the sheet ejects. This can be repeated until the printer has
"warmed up", which can take 10 - 15 minutes. It then prints complete pages,
although sometimes it sounds as if the carriage is slamming into the side of
the printer. After printing several pages the noise stops and it prints
normally.
Any ideas gratefully received.
Alan Duerden