TOPIC: Internal Server Error - Pay Later option

Joomla 1.5.20
DTRegister 2.7.4c

When I try to submit the pay later option I get:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Apache Server at www.myprizm.com Port 80

I didn't change anything. Is this a hosting issue? Thanks!

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