Brush size in PS CS4 cut off

Hi.
When I make the brush size for any tool bigger part of it will disappear. Only the small brush sizes are shown as complete circles.
This happens with all tools that use a brush size. If I make the brush bigger or zoom into the document only a small part of the brush size will be visible. This part of the brush is placed inside a square. The edge of this square cuts the cursor off at the bottom and right.
If I move something with the move tool and it's a bit fast, the same square size will pop up, dividing the object into squares.

This is very annoying. The first one makes it impossible to work in Photoshop since I can't use big brushes (with either pencil, brush, erasor): I can not see the cursor when the brush is big or if the document is zoomed in. If the document size is 100% and the brush is big the same thing happens.

Working on a brand new workstation. XP 2002 SP3.
Intel Quad corre Q9550 @2.83 Ghz.
I.98 Ghz 2.98 GB RAM.
Graphics card NVIDIA Quadro FX 1700.
Extra hard drive 1 Tb.

I hope to hear from you.

Do you have full size brush tip checked in the prefs?

There are dozens of posts you can read in this forum on this cursor problem.

Here's the clue: upgrade the video card driver to the latest version.

Thanks all.

Wolf. I have only recently installed this graphics card. I shall see if there is a new driver available and let you know if this fixes it.

Buko. Yes, of course ;-) Or one variety or another, depending on the needs.

John. Where, please? I logged into this forum late last night after a long day of teaching. I did look for posts about this topic before posting but obviously missed something here!

Thanks for the reactions.

I have just installed the new driver. It helped. Thank you very much. I suppose you can tell I don't know much about graphics cards since I took the seller's advice for granted: "Do I have to install something? There's this CD in the box..." "No, you don't have to install anything." Go figure. All happy now :-) On to exploring the new options.