Membership PayPal Renewal Redirect Too Many Times
It sounds like you've got a misconfiguration in your web server (Apache/nginx/etc.) configuration in your "rewrite rules".  You'll need to involve your web server administrator.

The easiest way to spot this is:


Go to the affected page.
Press "F12" to bring up Developer tools.
Select the "Network" tab.
Submit the form that causes the problem.


At this point, your Network tab should fill up with URLs it's trying to access.  My guess is it looks something like:

http://mysite.org/something/contribute
http://mysite.org/something/something/contribute
http://mysite.org/something/something/something/contribute
http://mysite.org/something/something/something/something/contribute


etc.

Compare that to your rewrite rules (if using Apache, be sure to check .htaccess files), looking for the "something" in your configuration.  That's the rule that's causing the issue.