500 Internal Server Error

I have recently been encountering a 500 internal server error when attempting to access downloadable files through my zencart web store. Everything is fine with the actual files and no changes were made before this started happening. I should also note that I had previous begun installing another web store, magento. When I attempt to access this store, I get the same error. I can access the zencart store just fine, but attempting to download digital products gives me this error.

“The server encountered an internal error or misconfiguration and was unable to complete your request.”

I have looked at the error log, but being an amateur, I can’t make heads or tails of it. Any thoughts?