sign up error with Supporter

I have just installed the supporter plugin on a multisite install using WP 3.0.1. I am using a testing server currently. When I logout and go to the registration page like a visitor would and sign-up, when I fill out the initial blog registration form, page 1 and 2, I then get the following errors. I don't get the pay-pal option showing, then if I login to the blog, it tells me that I am already a supporter, but I have not been directed to pay-pal to pay anything.

Warning: fopen(C:\xampp\htdocs\wp30test/wp-content/plugins/) [function.fopen]: failed to open stream: No such file or directory in C:\xampp\htdocs\wp30test\wp-includes\functions.php on line 4165

Warning: fread(): supplied argument is not a valid stream resource in C:\xampp\htdocs\wp30test\wp-includes\functions.php on line 4168

Warning: fclose(): supplied argument is not a valid stream resource in C:\xampp\htdocs\wp30test\wp-includes\functions.php on line 4171

What am I doing wrong. I was able to go in to Supporter settings and set everything, but I am not able to get the actual pay-pal integration to work.