I want to thank you for sending that file to me because it helped in solving our issue.
If you want the story it's as follows (with most of the boring stuff cut out so it seems like i solved it in 10 minutes).
I received your file with the statement that it worked fine. Opened it up and went to the Form1 designer.. BOOM! same error as before. Sent it to my colleague, who had the same error. Then because I was curious tried to compile the program to see what it ran like. This ALSO gave me an error, which was not occuring when we ran our native solution.
Looking at this error it said it couldn't find Infragistics 6.3.1056 (which is a previous HOTFIX). So I re-ran the IdeaBlade Assembly Binding Redirector. When I tried to compile your solution the same error came up.
This made me curious to see what was in the Machine.config file, so I went and opened it up and noticed that there were two binding redirects. One for Hotfix 1056 and another for Hotfix 1059. I removed the redirect for 1056 and ran your file. It worked... went into our solution and looked at one of the designer forms, works like a charm.
So just to let you know if you come across this with another customer, one of the things to check is the machine.config file for the correct redirects.
Again thanks for your time and effort. Without your quickApp never would have figured it out.