it means your computer is looking for someone to send it some work to do, to send back and that's when you get paid - submitting transaction work.

you can lose a connection to a pool for any number of reasons, eg:

1. your internet connection is down
2. you have the wrong pool settings
3. the pool is down
4. you haven't downloaded the right cgminer - try 1gh.com they have a download for cgminer 3.7.3
5. xyz reason.....

1. Try connecting to an 'Anonymous' pool which means you don't need to register, just enter your wallet address and point your miner at them. This will test any registration problems. Try dwarfpool.com or 1gh.com
2. Join a pool that requires registration.
3. Have your .bat file list a failover - mine on which pool you prefer, but have a failover to another in case your main pool server goes down, etc.