gmod resolution issue

for months now ive had an issue with gmod starting up and now i can start it up but only in 640by600 resolution.
as soon as i change the resolution in the menu my monitor crashes and the only thing i changed was my graphics card i got a nvidia geforce 9800gt and have it fully up to date so any ideas could help other than that heres my specs
dell insiron 530s with vista
nvidia geforce 9800gt 1024mb
2gb of ram
and whatever comes stock with the actual computer
never mind i did some computer voodoo and its fixed