FS 9 lock up with new FX5600

[Dougx]

I have upgraded my video cards over the last two years. 32meg, 64meg, 128meg and recently FX5600 XT 256meg. Each time I set the AGP aperature in bios accordingly. This time when I set aperature to 256 meg  FS9 will lock up within
a minute or so.  I changed it back to 128meg  and  all ok. I don't see any difference in frame rates whatever the setting.
Is it important that the aperature setting match the card? Any comments appreciated. Doug

    P4  2.4G
    512meg ram
    98 SE
    120G  h.d.

[congo]

No, the aperature isn't related to the video card's ram.