Reading Inner Html From A Frame Within A Password Protected Website

I'm making a macro that logs into a password protected site, then checks to see if new work has been assigned to a given user. To to this it uses the navigate method on a frame within the main document and reads the innerhtml of that frame's document (repeats if multiple pages exist). The problem I'm encountering is that only sometimes does the last 2 lines of the code below (double brackets = censored) work as intended:

Set objIE = CreateObject("InternetExplorer.Application")
With objIE
.navigate "[[website login page]]"
Do While .busy: DoEvents: Loop
Do While .readystate 4: DoEvents: Loop
.Visible = True
With .document.forms("params")
.UserId.Value = "[[User ID]]"
.Password.Value = "[[password]]"
.submit
End With
End With

Do While objIE.document.readystate "complete": DoEvents: Loop
objIE.document.frames("WorkspaceRight").navigate "[[new frame destination]]" .................