OK, I develop a telemarketting app that comes in two parts. There's a Telemarketting app and an Admin app.

I recently changed the development enviroment from VS 2005 to VS 2008 and when I did the last roll out the Admin app installer popped up a message saying that it now required the 3.5 framework. I'm really not sure what introduced the new dependency because the only change in the new version was an additional checkbox on a form along with the ammended code to read and write the assosciated value back to the DB - nothing that isn't done a thousand times already elsewhere in the app.

I didn't particularly let that worry me though because the whole point of upping to 2008 was to use some of the new features and that means sooner or later we'd need to upgrade the framework on the target machines anyway. So the IT Support guy here grabbed the 3.5 framework download. He installed it on our test machine and everything was peachy and extracted the contents and deployed the msis through group policies. Immediately he did this the telemarketting app (which is a bit business critical) started keeling over and refuses to start. We've got round the problem for now by reverting the target machines back to 2.0 so there's no panic but this does leave me unable to roll out the admin app.

The error we get when trying start the telemarketting app reads:-
EventType clr20r3, P1 telemarketing.exe, P2 1.0.0.75, P3 48bfec57, P4 system.configuration, P5 2.0.0.0, P6 471ebf00, P7 27b, P8 a, P9 ioibmurhynrxkw0zxkyrvfn0boyyufow, P10 NIL.
I don't have experience of reading these but from googling a bit I gather that the error message is contained in P9 - so the error is:
ioibmurhynrxkw0zxkyrvfn0boyyufow

That looks like garbage to me but I was surprised to see that googling it returns lots of results and the general theme seems to be that it's a corrupt config file. We've grabbed a config file from a target machine and put that on the test machine and it worked fine - which implies that the config isn't the problem.

At this point I'm stumped. can anyone suggest what we should be checking next?