This is a strange issue that you are observing and we will need more details about your project so we can provide you with a solution. First of all tell us more about your project - what set up are you using - database, server, NLB, cloud hosting. Any piece of information will help us. Please send us your Error.log file so we can inspect the errors. It is located under App_Data\Sitefinity\Logs
If possible create an administrator backend user for us we can check what is going on with the blogs.
As a last option consider sending us your project so we can debug the problem locally if it is reproducible on local environment.