I also am have the same problem with VRBO. Customer support told me it would be at least 2 weeks or more to fix. Other then this problem we have received several inquires and I can send a reply as long as it is without a quote.

The problem is with the reservation manager part.

I am having exact same problem and am extremely frustrated too! Just joined HomeAway on May 21st and cannot send quotes only replies through Reservation Manager.  Today I tried to send my first booking and payment request through Reservation Manager and Error came up and did not go through.  I called support at first they said they were not having any problem and it could be my computer or browser I was using.  Had me open up a different browser and log in and go through the whole process of attempting to resend.  I did and got same result!  He had me read him what the error message said.  After putting me on hold for quite awhile, came back and said oh yes he was told by tech. support there is a problem effecting some users and they are working on it.  Could not give me a time when it would be fixed!  Am very frustrated.  We have just purchased our vacation condo and am new to the rental market...thought HomeAway's online payment processing was the way to go.  Apparently they do not have the kinks worked out or they are buying up too many of their competitors and growing faster then they can keep up with technology!