I could not beleive it when i figured out why a click once application would not start on one of the networks machines. Over the past few days I have been helping a few people install our main business application from click once rather than over the network as it has been for the last 12 months, All was going well except for one machine. I tried reinstalling .NET 2.0 framework and going through the registry looking for any references that may have been left behind but to no avail.

Our user naming convention is firstname and first letter of last name, this one particular users account was firstname.lastname noticing this I logged on using my domain account and sure enough my clickonce started working properly.

So it seems having a full stop in the login username causes the software to fail with this mesage
The system cannot find the path specified. (Exception from HRESULT: 0x80070003)

Crazy I know. but true.