Why does my installed application fail to run?

I've got a .NET 3.5 Application that was working well. The installation was also working and the application functioned properly after installation.

I've fixed a few bugs and rebuilt the setup but now I can't get the installed application to run. I'm completely removing the ol开发者_Go百科d install, re-installing and when I run it I get the:

Data Tool has stopped working...
Windows is checking for a solution to the problem...

• I don't even get a .net exception...
• Running from the release folder works.
• If I copy the files from the release folder into (and overwrite) 'Program Files' it runs

Any ideas?

Update:

I'm using a VS2008 deployment project to build my installer...

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Deleted and re-added the 'Primary Output' in the setup project and it appears to have fixed it.
I've been trying to work this out all morning!