Sounds like an issue previously reported here. For More Information see: Edit Layout/Report in Pro 11 Screen turns to gray when using either of the scroll bars.
This is one of many acknowledged bugs that can be found in the Known Bug List here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: http://www.4shared.com/file/8orL8apk/FMP_Bugs.html
Thank you for your post.
As PhilModJunk reported (Thank you!), we are aware of this issue. I have attached your post to the original case. When more information becomes available, I will post here.