Sphinx failed to read searchd response

Question

I have strange behavior of Sphinx searchd. I used it with Python standard client on ubuntu 9.10

For same query it's can give normal response or can give broken package like this: failed to read searchd response (status=0,ver=1,len=278,read=72)

this problem appears with 50% probability.

I have test index with only 5 documents and default config.

Will be grateful for help)