Graphic card error code 39

Hi!
A have a problem with nVidia GeForce 4 MX 440. Sometimes
it doesn't work propertly and in system menu "Hardware
(configuration? or manager?)" {(Excuse me, I have czech
Windows XP Professional, because I am from Czech Rep.)}
there is "(!) in small yellow field" in front of Graphics
card. Windows give message to me: "Error code 39 - some
driver is not install or missing" (I thnink). After
reinstall nVidia drivers it works correctly. But
sometimes it crashes again.
Please contact me, what is the problem.
I have MB Matsonic MS8147C with VIA KT400 chipset and
256MB DDR400 memory.
Thank's.
Lukas Booch < booch@tiscali.cz >