I have the following brand new Dell system

Dimension 8400 P4 processor 640 (3.20GHz,800FSB,2MB cache)
1024MB Dual Channel DDR2 400MHz Memory (2x512)
3.5" Floppy Drive
320GB SATA RAID 0 Stripe (1st (2x) 160GB 7200rpm) Hard Drive
2nd 160GB (7200rpm) SATA Hard Drive RAID Only
16x max. DVD+/-RW and 16x DVD
FP/MG - UK/Irish - 17in (1704FPT HAS TCO99) UltraSharp Midnight Grey Flat 
Panel Monitor
128MB PCI Express ATI RadeonTM X300 SE

I am using Corel Draw 11. The problem I have is when I zoom into or
out of a drawing, using mouse scroll wheel, part of the screen just
goes white (blank). I have to toggle to another application (Alt +
Tab) and then come back for the drawing to show up. These are simple
black line art drawings and a high spec PC such as above should be
able to cope very easily.

My screen setting is set to 1280 X 1024 at 75Hz (I have tried 60Hz as well)

1) What is the likely cause of this problem?
2) How can I resolve?

Any help will be greatly appreciated.