CSV Export Problems

Hi
We've sent you a separate note about another issue via the Contact Us form, but meanwhile have a bit of a more immediate problem.
We have just run a survey and obtained about 1000 responses. Whilst small scale testing the CSV export option worked just fine. However, now the CSV output just hangs and creates a blank page (in Chrome) and Error 500 (in Explorer).
Is there anything we can do to get this extracted quickly/what is causing this problem?
Many thanks
Matt