You should set response.buffer=true. But if you do not set this, it should give an error.
I would suggest putting response.buffer=false so that whatever is ready for display will get displayed in browser immediately.
If you are putting all your code in a single outer table, then flushing the buffer is not of any use. Some browsers will wait till the ending table tag is found.
You may breakup the page into a number of small small horizontal tables of equal width and same alignment, you can override this problem.
BTW, have you heard about table-less design ? You may visit following links in your free time.
http://glish.com/css/
www.zeldman.com
www.csszengarden.com