Blank page after review order in paypal pro payment method

I am getting blank page at time of submitting order using paypal pro account on my site.

I have check my server log an it give me error message of :

[Sat Feb 04 01:35:49 2012] [error] [client 66.249.67.9] Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.

site url is http://webworldinfotech.com/demo/user/register

Thanks.... Devang