Not enough info to answer. What other info is in SharePoint Logs? Try to attach debugger or use logging. Most likely smth is not initialized before accessing.

UPD: Are all resources used be the page published?

Not enough info to answer. What other info is in SharePoint Logs? Try to attach debugger or use logging. Most likely smth is not initialized before accessing.

UPD: Are all resources used be the page published?

UPD2: MichaelF has a point. Have you tired using smth like:

SPSecurity.RunWithElevatedPrivileges(delegate
{
 // Code goes here
}

?

Not enough info to answer. What other info is in SharePoint Logs? Try to attach debugger or use logging. Most likely smth is not initialized before accessing.

Not enough info to answer. What other info is in SharePoint Logs? Try to attach debugger or use logging. Most likely smth is not initialized before accessing.

UPD: Are all resources used be the page published?