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.