Seems others are reporting this problem too, but...
Two 7970's indicate a hashrate of over 1 mh/s, but litecoinpool indicates my worker is at ~70 k/hashes. WTF?
Im having this same problem just now, one of my 7950 indicating false kh/s on the pool.vi solved it just by restarting the computer. Btw im using guiminer 0.03 + cgminer.