citrix receiver error 1046 the virtual driver is not loaded

On one of our Windows 7 pc's we get the error: This version of Citrix Receiver does not support selected encryption. Please contact your administrator. (error 1046: the virtual driver is not loaded)

The error happend over night, no idea what the cause is.
I tried reinstalling the Citrix receiver (13.1.0.89), but same result. Even used the Citrix ReceiverCleanupUtility to remove all registry settings concerned and installing again: same result. Tried the latest version of the Citrix Receiver: same result.

Funny thing is: I have about 40 pc's all running the exact same configuration and Citrix receiver version, but we (luckily) only have this problem on one pc.

I also tried a system restore to an image from a couple of days ago when everything worked, just to rule out any windows update errors: same result.

Any ideas how to fix this? (other than a complete reinstall of the pc)

regards,

Frank