Error when checking out with Paypal

I did try to search for a thread about this error already, I apologize if I overlooked it.

I'm getting the following error when I try to use paypal express to check out (everything runs smoothly when selecting another payment method.)

"Warning: Header may not contain more than a single header, new line detected. in /homepages/6/d214037818/htdocs/wsb4608872601/store/includes/functions/functions_general.php on line 44"

I'm still new at this and I'm not very experienced with the code... does anybody have any suggestions? I'd appreciate it - Thank you!

Are you using v1.3.7 or v1.3.7.1 ?
What version of PHP?
Who are you hosted with?
What's your site URL?
What FTP program do you use?

I'm using Zencart 1.3.7, I'm also using Extra Colors 1.3.5. I was instructed last night to download the bundle patch to fix my other problem but have not done that yet.

I'm hosted with 1and1.com; my url is www.imperishablebeauty.com.
I'm using Filezilla 3.0.0-rc2 and I'm not sure what PHP I'm using - whatever came with my initial download.

Does that help?

Upgrading to v1.3.7.1 instead of 1.3.7 will likely help resolve this issue.