Vertical lines are breaking up

Last week I installed a new graphics card. Nvidia e-GeForce 8400GS. I loaded all available drivers. AutoCad LT 2006 is now having problems with vertical lines while I'm panning. I can draw a vertical line and then pan and the line appears to break up. I've spoken with Nvidia and have determined that it's not the new card. I have also done unistall/re-installs on both the graphics card and AutoCad Lt 2006. How do I fix this annoying problem?

When you say "breaking up" does it mean that it appears as portions of the vertical lines are missing or that their appearance is "jagged"?

As I pan with the mouse, all vertical lines including the cursor appear to become "jagged" as the images move across the monitor.

It's a function of the resolution of your graphics card and the viewing angle of your monitor. I've had it happen to me. I'll swear that a perfectly straight vertical line has been drawn at a very slight angle. To verify the line is indeed straight just highlight it and click on properties.

What resolution are you using?

When you pan is it at a fast speed? Perhaps there is a "lag" in there. Can you check and tweak your mouse settings?

Let me be more clear. I can draw a perfectly straight vertical line, and then pan the entire screen with my mouse. While panning, the vertical line I just drew is breaking up wildly, or becoming very jagged as I pan.

Then it is definitely the refresh rate of your graphics card. Period.

how do I change the refresh rate of the graphics card? It is a Nvidia e-GeForce 8400GS. I think the refresh rate is set to 72. My screen res is at 1280x1024.

I've tried everything I can think of. I don't think it's the refresh rate. I've tried setting it higher and it does nothing to solve my problem.

Sounds like a driver problem to me. Check out AutoDesk's website for their recommended driver rather than the one from nVidea.

How old is this system? Could it be heat buildup from an accummulation of dust? Heat can do strange things to a computer.

It's not very old. Less than two years. I recently cleaned out all the dust. Can anyone tell me how to get to the hardware accelerater? I think maybe that box is unchecked...I just can't seem to find it. My current system is AutoCad LT 2006.

Try the 3DCONFIG command.