line 1 char 1 error object expected code 0 url http//www.dell.co.uk/ error on page

i receive a yellow triangle with error on page when i browse internet.  can anyone tell me why and how to fix this?  sometimes the line/char nos change and error is 'html' is null or not an object.  items on the page will not let me edit them or some pictures are just red x''s.

i'm running vista home premium with i.e as my browser.  thanks for any help at all as this is driving me nuts.