Cache troubles?

Strange problem with (I think) cache module
Main page returns this error

Warning: gzinflate(): buffer error in .../includes/bootstrap.inc on line 454

Warning: Cannot modify header information - headers already sent by (output started at .../includes/bootstrap.inc:454) in .../includes/bootstrap.inc on line 465

After I clean the cache by "delete from cache" query everything back to work fine until next refresh or other user enter. Then the problem back.

What's wrong? This woked fine before