hi guys i got an error can u help "run-time error 91 object variable or with block v"

hi guys i got an error can u help "run-time error 91 object variable or with block variable not set"

my application imports a list from a text file and shells each line and tests the results.
i am using these functions

while loops
do while loops
goto commands ("i know its bad :)")
i have text boxes
im using 3 timers
and using webbrowser

without me posting my entire code here could you give me a clue as where to start looking please :)
and i only seem to get this error after a few loops of the entire process. not quite sure why it would error out as the first few times were successfull

BTW im jerry nice to meet you all