We have been using CSS3 within SharePoint for almost 12 months now and in this time we have used the PIE.htc file to enable us to have CSS3 capabilites in older browsers such as IE7 and IE8.

If you use the pie file within the style library like – behavior:url(style library/pie.htc) or within the css file location itself  – (behavior:url(pie.htc) ) then the pages using the style will redirect to a blank page within IE.

When setting the location of the PIE file in the behaviour tag you will need to make sure that its done as shown behavior:url(/_layouts/pie.htc) to prevent this from happening