Why did the North Pole's computer network keep crashing?

It was suffering from too many 'frost-bytes'!

Why did the head elf install a new time clock in the workshop?

He wanted to make sure everyone was working around the claus.

What do you call Santa's fear of being stuck in chimneys?

Claus-trophobia.

Why was Santa's little helper feeling depressed?

Because he had low elf-esteem.