The Aspergian mental processor chip has a limited data gateway. We process information and stimuli just fine as long as its not coming through the system too fast. When we're trying to multitask too many ideas simultaneously, or perform almost any mental function under stress (which includes the stress of social interaction, where we are bombarded with nonverbal signals and our brain tries to focus on those and interpret them while processing other input at the same time), it's like trying to shove too much data through the processor's gateway at once, or 'shoving mud through a funnel'.
To me it feels the same as when you're computer's hourglass (now a spinning circle in Vista and 7) just spins and spins and you get that message that the program you're trying to run has 'stopped responding'. You can either sit there and wait for the brain to catch up, or just dump everything and start over.
Glad to know I'm ot the only one that uses computer terminology to explain my head.