experiencing lockup

appreciate any suggestions. I periodically experience lockups primarily when switching views, panel to spot for example. I often get the dreaded Microsoft window, closing the program or I have to reboot. I recently changed display settings to 1280x1024 from 1024x768. This was done to reduce my numerous icons to a smaller size. Intuition tells me I may be taxing my graphics card more with the new settings? Might this be the cause?
P4 @ 2.4G
Visiontek GF4 MX420 64meg
512 ddr ram
17" monitor, 40g hd, all sliders maxed
P4 @ 2.4G
Visiontek GF4 MX420 64meg
512 ddr ram
17" monitor, 40g hd, all sliders maxed