First we need to know your pc's spec's , operating system , video drivers , background programs that are running (such as fire walls/AV's ect )
Such as
2.0 ghz Amd
512 ram
gf 4 mx 400 30.85 drivers Direct X 8.1
win 98 se
microtrends AV program , set to manual scan
700kbps Dsl connection