Why didn't the Potters disapparate?

[Vicki Granger]

No: HPFGUIDX 23178

Catriona Wrote:
Ack! I'd forgotten all about splinching ...legs in one place, body in 
another.

~I'd always imagined it as in-half the other way, slit head to toe 
through the middle. More grusome ;-)

To repeat the same quote from the books:

In Book 4 Arthur Weasley says:
"It's not easy, Apparation, and when it's not done properly it can  
lead to nasty complications. The pair I'm talking about went and  
splinched themselves." 

He says nasty complication*S*, the plural, more than one... So what 
are the others? Disapearing off the face of the Earth completely?

~*Vicki*~