How to resolve SystemArgumentException: The path is not of a legal form error in Citrix Receiver

I have been getting this error in Receiver 4.1 quite a lot recently.

It seems to occur when you upgrade or reinstall Receiver.

The fix is to rebuild your profile but I have have a more targeted fix which I have outlined below:

1. Close down Receiver

2. Terminate the process wfcrun.exe using Task Manager. The process may restart itself and require terminating for a second time.

3. Delete %APPDATA%ICA Client

4. Log off and back on again the problem should be resolved.