Writing new entries to database stops, unexpectedly (1 reply)

I'm using MySQL with Entity Framework, my database contains 4 tables. At the beginning everything works good, but after a month or so, when db size exceeds 40 MB (approximately 180000 rows), writing new entries to the db stops, no errors at C# side. After I empty the tables and restart my program, writing entries starts again.

Note: db optimization and practices not used. Over 1 TB free hard disk space, 8 GB ram installed.

Is there any limitation, If not how can I find the problem? I can post InnoDB monitor output, if helpful.