Master Page with menu that disappears over a report

[Carolina]

Hi,

I have a Master Page with a menu and a Content Place Holder. I have created
a new aspx page having this Master Page as a base. Then I placed a
CrystalReportViewer in it to see a report. The problem is that when i run it
the Menu items that are over the Crystal Report when are displayed just
dissapear.

Does anyone know how to fix this problem?

Thanks in advanced.