the screen is going blank while printing

I have the following problem:

I have an MDI-Application with 4 splitter-windows. Each splitter-window has 3 splitters. Now i want to print data from one Splitter (used as a List-Report-View).
I need to print a lot of that data, but when i do so , the whole Application-Window gets blank - there is only white space left. When the printing is finished the screen restore and everything is ok - What can i do to prevent the window from going blank while printing ?
(I suggest that a must put an certain function call in the print-loop ?)


thanx in advance for your help

I have forgotton to say how i print the Data:
I simply use C-Command like 'fwrite' etc encaplulated in a class, which gets here data from the Report-View and print the data in a loop.