If I had internet access at my house(long story) I would have know this and not recompiled NUnit using the 1.1 framework:
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Here is another solution to get NUnit up and running with Framework 1.1:
The fix is simple and it is incorporated into 2.1. Until then just make the following change to the configuration files, nunit-gui.exe.config and nunit-console.exe.config.
<?xml version ="1.0"?>
<configuration>
<startup>
<supportedRuntime version="v1.1.4322" />
</startup>
</configuration>
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I am fully convinced that internet access increases my productivity by at least 2-3 times.