cubase 4 hangs when 'loading channel out'

i installed a new graphics card and then when i tried to load my project, cubase 4 hangs at the ‘loading channel out’ stage. i managed to deactivate the plugs ins in my project that are used in the out channel in the plug in manager. this then allows me to load the project. i then moved the offending plug in higher up in the slot list in the out channel, saved the project, closed cubase opened it again and loaded the newly saved project and the project loads fine. what is that all about? not ideal… what else am i going to find has gone wrong having installed a new graphics card. any ideas or suggestions much appreciated…