Use conditional logic to help users, not burden them

A colleague sent me this error message from PayPal. It lists out all the conditions that could have lead to the error using a series of "IF" statements; each condition requires a different resolution (click to see full-sized image):

Rather than using the conditional logic to create a separate error message for each case, PayPal  makes the user wade through the IF statements to determine which case applies. This makes it particularly difficult to find the resolution. Errors are never a happy circumstance for users; by making error recovery more difficult than it needs be, the aggravation is compounded.