Textbox, HTML Tags & RegularExpressionValidator

[RKP]

Hi

I have a web page containing a multiline text box that users regularly paste
HTML output into.

On postback the page errors.

I've tried to get around this using a RegularExpressionValidator with some
success but cant seem to nail it.

Is there a better way or can someone please provide me with a workable
ValidationExpression.

TIA

Richard