Refresh servlet page problem

[andrew tollin]

Hello I have a problem with my servlets. I have created a number of servlets that connect to a database, access a particular table, and insert the database information into skeletal HTML. When I view my page on Tomcat port 8090(changed from port 8080 due to DB probs) by entering http://localhost:8090/servlet/UsefulAddresses for example, it loads with no errors. However when I refresh the page I get this error: Error: 500: Location: /servlet/UsefulAddresses: Internal Servlet Error: : java.lang.NullPointerException  at org.gjt.mm.mysql.Statement.executeQuery(Statement.java)  at org.gjt.mm.mysql.jdbc2.Statement.executeQuery(Statement.java:78)  at UsefulAddresses.doGet(UsefulAddresses.java:50) If i enter the servlet URL in the address bar again press return it returns to the error free page! Every time I refresh this page or any other of my servlets I get this error. Could anyone please tell me why this is. My servlet code is the next email. Andrew