messagebox, showdialog and threads error

Hi,

I'm having a weird problem.
I use a thread to generate a lot of data in c#, and at the end of the thread I sould have a messagebox that show. If I execute the code two time, everything work great, but if I execute it a third time, the messagebox doesn't appeir.

I check in the debug and the line is executed but nothing is show.

Then I try to change the messagebox to a custom form with a showdialog. The two first time, everything work fine, exept that showdialog is executed like a simple show. But the third time, the debug stop at the line where I create the form (frmTest t = new frmTest();) and make a infinit loop at t.showDialog(); without never giving error...

I try a lot of stuff like abord the thread at the last line of the thread, or use a delegate, and nothing work...

By the way, sorry for my english.