how can I prevent this from causing an error?

[dunfiddlin]

so how can I wait for the form1.webbrowser1 to load from within a loop (which involves navigating multiple websites) or from outside of form1 without using application.doevents()

I already indicated two possible answers. Either use the DocumentCompleted event to check for the presence of a specific item in the current page so obviating the need for a wait loop, or use WebClient to download the source HTML for each page which requires no attention at all.