Object reference not set error on seventh tab

[MArkB]

This is the full error
"Sys.WebForms.PageRequestManagerServerErrorException: Object reference not set to an instance of an object."

It happens when I click on a tab after clicking on the seventh tab. When I use any of the first six tabs in behaves just fine. Once I click on this seventh tab I get the error when I click on any of the rest of them. If I switch the tab order in the code the problem is still with the seventh tab.

Right now, I'm just asking if this is a known bug or if someone has experienced or heard of it in the past. If it's unheard of I'll post more information.
Version: 2012.3.1205.40
Runtime Version: v4.0.30319

I'd rather not post all the code to the general public right now. I'm getting the account information from our admin so I can submit a ticket.

MArk B.

[MArkB]

Just to close out this issue, I upgraded the controls to a later build and it's working just fine now. Don't know what the cause was.